Let me preface this by saying that this is a work in progress, and for now, only includes basic Grid. Eventually I will extend it to cover some of the more useful Grid additions (mainly for healing), but for now, enjoy!
I'll start with what Grid does and where to download it.
Grid is a completely customizable, condensed version of the Blizzard default raid frames. The basic Grid download comes with options to show health deficit (how much hp is missing) track: incoming heals, hots, auras, buffs, debuffs, aggro via corner icons, lot mana indicator, icons for dispellable debuffs, and much much more.
You can download basic Grid Here.
Now then! The basics!
This is what grid looks like when you first install it.
Not very pretty is it? It also makes it hard to see some information (like the name of the offline/dead player).
We're going to make it look like this instead.
So! Here are the steps to make it to that nicer looking grid!
Before you start! I recommend you join a raid (either as an extra member) or an AV, so you can see what size the Grid area will be when you are in a large group.
Left Click on the Grid icon on your minimap. This is the easiest way to customize your grid. You can Right click on the icon, and scroll through the options there, but I've always found it easier to use the full menu.
1. First we're going to invert the colors, so the boxes start out class colored, and turn black as HP decreases.
Click on Frame, and in the right hand side of that window, check the box marked Invert Bar Color.
(This is also where you go to change the center text length. by default it shows the first 4 letters, which is enough for me, but you may choose to make your grid wider and have more room)
2. Next we are going to get rid of that horrible border around it, and make them less spaced out. (The whole point behind grid is to save screen space vs the blizzard raid frames, while displaying as much or more info)
Click on Layout, and in the right hand side of that window, move the scroll bars labeled Padding and Spacing down to 0.
While we are here in this window, let's set the display for the different group sizes. You can set these each to the smallest size possible for that group size (ie party would be by group 5) or you can set them by the largest (by group 40 with pets). I usually keep them at the default settings which are
Solo: Group 5
Party: Group 5 (w/pets if I am a pet playing class or a healer)
10 player Raid: Group 10 (w/pets if I am a pet playing class or a healer)
25 player Raid: Group 25 (never w/pets because it can take up too much space)
Battleground: Group 40
Arena: Group 5 (w/pets if I am a pet playing class or a healer)
To make the border and background transparent, scroll down on this same page, and click on the White Box next to Border, and move the slider bar on the right all the way to the bottom. Repeat what you just did, only for the Black Box next to Background.
3. Now we're going to change the Size of the character boxes.
Go to Frame -->Advanced and scroll down until you see Frame Height and Frame Width. Make these as as large as you like. They don't have to be square (although I prefer them to be unless I'm on my tree). You can either click the slider bar and move it up or down, or type in a specific number. If you use the slider bar, it will automatically update as you move it. If you manually typed in numbers, you have to press enter after changing the value. ( For most of my characters I have this set to 34x34)
4. Now we're going to add a second Center Text, and configure the both Center Texts to show what we want. Center Text is the text that shows up in each character box.
Go to Frame --> Advanced and check the box at the top that says Enable Center Text 2 Indicator.
Now go to Frame --> Center Text. I use the first center text to only show the name. (because no matter what you need to know which box is who) Uncheck everything except Unit Name.
Now go to Frame --> Center Text 2. Check all the things you want shown as text (this will be the text underneath the Name). For all of my characters, I only check:
Death Warning ---- Says Dead
Debuff: Ghost ---- Says Ghost
Health Deficit ---- Shows # of HP missing (ie -1400) scales off of max % HP. This threshold can be changed in step 9
Offline Warning ---- Says Offline
5. Now we're going to configure the center icons. I usually set these to show only what my character can remove (ie Mage it would only show curses, on a Warrior I would not show any). On my healers, however, I usually enable all debuff types, because even if I can't remove them it lets me see who's going to be taking more damage.
Go to Frame --> Center Icon and only check the debuffs that you want shown. By default all four debuff types (curse, magic, poison and disease) and Ready Check (only shows if you are a raid leader or assist) are checked.
6. If you are a class without heals or targeted buffs (ie a warrior) you can skip this section. Now we're going to play with our buffs/hots/etc that appear in the corners! First things first, let's make sure the corner size is a good size. Go to Frame --> Advanced and find the slider next to Corner Size. Slide this bar up or down until you get a box that's big enough to see, but not so big you can't read your center text. I usually choose anywhere from 5-10, depending on how large each grid box is.
7. Now I'm going to show you how to add Buffs (or Debuffs) so you can track them with grid, either with Icons or using the corner indicators. You can skip this section if you have no buffs/debuffs you wish to track via grid.
Go to Status --> Auras. You will see two boxes on the right, one labeled Add new Buff and one labeled Add new Debuff. For a buff, simply type in the EXACT name of the buff as it appears in your spellbook into the Add new Debuff box. For example, I would type Power Word: Fortitude NOT power word fortitude or fortitude. The name must be exact, or it will not show up on your grid. Punctuation, capitalization and spelling all matter. For a new Debuff, do the same thing, but type the name of the debuff into the Add new Debuff box. Again, the name must be EXACTLY as it appears in your combat log or it will not work.
7a. Now we're going to change what colors each buff (or debuff) show on your grid.
Go to Status --> Auras --> Buff/Debuff Name. At the top is a color box. Click it, and select the color you want it to show on your grid. I recommend using the same color for single target and group buffs (ie single Fort and group Fort). Make sure it's a color you will be able to see easily. You can also select a priority for each Buff/Debuff. I only set a priority if I have more than one Buff/Debuff selected for a corner (ie for Anub'arak, I have Penetrating Cold set to show up in the top left, the same place where I show aggro. I set aggro to 90% and PC to 99% so PC will override aggro if both are on the same target).
8. Now we're going to figure out what corner shows what information. If you skipped section 6 and 7, you can follow this step to remove any unnecessary clutter (for instance, on my warlock I only use corners to show aggro). We'll do this one corner at a time.
Go to Frame --> Top Left Corner. By default, this corner only shows who has Aggro. I usually don't put anything else on this corner, because no matter what I'm playing, I always need to know who has aggro on a mob.
Go to Frame --> Top Right Corner and check one buff (or buffs) you want shown. For instance, on my priest I check Buff: Power Word:Fortitude and Prayer of Fortitude. It's important to check both ranks (if you have a single target vs group buff). If you don't have buffs to give, uncheck everything.
Go to Frame --> Bottom Left Corner and check the buff/buffs you want shown. By default this corner shows Incoming Heals, without differentiating on what type of heal it is, or who it's from. If you don't need this corner to keep track of a buff or hot, I highly recommend keeping it as it is by default, even if you aren't a healer, because it's a nice indicator that you don't have a heal coming and should probably use that health pot/stone. Again, if there is a single target and group version of the spell, check both. If you don't have buffs to give, uncheck everything.
Go to Frame --> Bottom Right Corner and do the same thing as you did for the last two corners, selecting different buffs.
9. Health Deficit. I've had people complain that Grid is 'slow' at showing missing HP, or doesn't show smaller amounts of missing HP. Both of these can be changed easily enough.
Go to Status --> Health --> Health Deficit and move both scroll bars up to 99. Make sure this is also Enabled. This will force Grid to update health changes instantly, and show the amount of HP missing, no matter how small. If you don't want to know if your tank is missing <1k hp, you can change the Health threshold to like 90%, but I wouldn't go any lower than that.
10. The last few steps I'll condense into one, since they mostly just make things a little nicer to look at.
First to to Frame --> Border. This is the colored border that surrounds each character box. By default it shows Low Mana, Low Health, and Your Target. I usually uncheck everything except Your Target (because most of my chars can't do anything about low mana, and I can see when someone has low health).
Now go to Status --> Auras --> Health and uncheck the box that says show dead at full health. This is VERY annoying to see a dead person as fully alive because at a glance it looks like you have more people active than you actually do.
Now go to Status --> Auras --> Range --> More than 40 yards (and More than 100 yards) and make sure both 'enabled' boxes are checked. You can uncheck the other ranges listed if you want to, but it doesn't really matter.
Now go to Frame --> Frame Alpha and uncheck everything except More than 40 yards and More than 100 yards. This will make the transparency of party/raid members that are 40+ yards much greater, so you can see at a glance who's missing from the instance or out of range. If you want to change the transparencies for each range, go back to Status --> Auras --> Range --> More than 40 yards (and More than 100 yards) and use the color picker to change it via the slider bar. Try to keep the 40 yards around half transparency, and more than 100 yards at 25% or lower (so you can see at a glance who's just a little out of your range and who's completely out of the instance).
The last thing we'll do is make all the unit names white (because I think it's prettier and easier to read). To do this, go to Status --> Unit Name and uncheck the box that says use class color. By default the color picker box will be set to white, but you can change this to any color (I recommend white, however, as when a target is dead/at low hp it shows up the best against the black).
Congratulations, you have now configured your Grid to be visually appealing and highly functional!
Once you have configured Grid for one character, you can go to Profiles and select 'Copy from' Character Name for any other characters. If, however, you use Grid for tracking different things on different characters (or like it in a different spot/size), I highly recommend setting it up from scratch for each character. It's time consuming, but switching profiles or having to reset everything when you swap between characters can get annoying.