Modding!

Personally, one of the things I enjoy most about Knights of the Old Republic is the ability to mod it. This post will serve as an intro for those who don't know how to modify KotOR and a reclist for those that do.

Where to get mods:
Nexus and Deadlystream are the big two.
There used to be a site called filefront that recently bit the dust after a decade of trusty service, but some clever souls have been uploading the files from that site onto the Nexus. Legally shady? Yeah, a bit. But also an absolute lifesaver.

How to install mods:
You can install mods on Windows and Macs very easily, as long as you pay close attention to what you're doing.

First, you'll need to know where your Override folder is.
For windows users, go to your Program Files and find the game. It'll either be under \lucasarts\swkotor or \Program Files\Steam\steamapps\common\swkotor, depending on whether you bought kotor retail or through steam.
For mac users, it'll be under \User\Library\ApplicationSupport\ **Steam**\SteamApps\common\swkotor. Yes, it's under Steam in the AppSupport folder, not under Knights of the Old Republic. That's just where it sticks your saves.
If there isn't already a file called "Override" in there, make one. Simple.

Second, what type of mod is it? Is it a drag-and-drop mod like VP's Hi-Poly Tin Cans? Or is it one with a TSLPatcher, like Bi Carth?

For most simple mods, such as reskins, they're going to be drag-and-drops. All you have to do is drag the files into your Override and you're set. For mods with a TSLPatcher, all you need to do is point the TSLPatcher at your game and let it do its job. The only reason I make a big fuss about this is that many older mods are from the times before TSLPatcher saved our lives. If any drag-and-drop mod alters a .2da file, you want to install it early.

A .2da file, such as appearance.2da, is basically a big spreadsheet that the game draws upon.
"I need Bastila in this scene. What does she look like? Let's check appearance.2da!" And then appearance.2da will tell the game what files it should be looking for.
Most of the time simple reskins don't need to touch appearance.2da- but if, say, a mod wants to do something like... Give Bastila her own unique set of underwear, not shared with the rest of the women in the game? A modder would have to alter appearance.2da and tell it to tell the game to look for a different file that they've provided.
TSLPatcher is nifty in that it checks for .2da files already in the Override. If it finds one, it can alter distinct cells within the file, so if you have a mod that gives Bastila nice underwear and a mod that gives Carth nice underwear, you don't have to choose between them.
It can also do other things like compile scripts and add soundsets to the game, but the .2da file bit is the part I actually understand.

Personally, I recommend copying files into your Override rather than just dragging and dropping, so you remember what file came from what mod. I also number the folders in the order that I installed them, so I know what mods will be affected if I want to take them out later.
Remember, KotOR does not support folders within the Override folder! If you try to do something like \Override\reskins, It Just Won't Work.
(Apparently it works for TSL, but I'm too wary of file conflicts to create subfolders.)

If you intend to mod your Steam version of TSL through the workshop, read this before you do anything. It'll save you a world of pain. It also has a great list of TSL mods.

What mods should I install?:
I, and I'm sure several others, will let you know in the comments.

And remember, if you have any questions about a mod that doesn't work or how to make mods yourself or anything, I will absolutely jump on any opportunity to talk about this. Seriously, you'd be doing me a favor by asking, so go ahead!