I loved Kotor 1 back in the day but have come to find out that Kotor 2 is far better and less lib (?). I know it's kind of an unfinished game with lots of bugs but I also heard people made it complete over the years.
What are the essential mods for Kotor 2 that I should install before I play?
TSLRCM restores content and fixes bugs, it isn't as essential as people make it out to be, but it is nice
TSLRCM Tweak Pack unrestores things that were clearly cut because they were shite and not because obsidian ran out of time
K2CP fixes bugs and things that TSLRCM didn't
pretty much everything else is retextures and shit, so grab whatever looks cool to you
The plot triggers on Nar Shadda can be a real finicky mess. Talk to literally everyone there. You have to make almost every interaction imaginable happen before you get your local reputation high enough for the plot to move forward. Even with the best fixes and mods, that planet in particular is bug central.
Save often, in general.
And have fun. It'll feel slow at times but it's absolutely worth it, especially with the restoration mods.
In addition to everything else, you should know that the first planet, arguably the first two, are kind of infamous for being slow and boring. You definitely need the context you gain from playing each of them once, but for subsequent playthroughs there are mods for skipping the first one. Just power through. Some people find the first planet a lot less odious if they spend time reading/watching all the available logs- it's kinda sorta meant to be like a horror level, but for the most part it doesn't really land.
I would honestly recommend skipping the Restored Content Mod. I've found that a lot of what it restores isn't necessary, some is tedious, and in a couple places it broke my game hard enough that I had to reload hours-old saves to fix it. A lot of what it restores in the end game is pretty good though- it's a tough call.
Kotor2 rebalanced combat so that the basic lightsaber build is no longer the only real viable one. You can still totally do that if you want, but blaster builds and even unarmed builds are very good now too (EDIT: also, there's a couple melee weapons that you could honestly use over lightsabers. Like not in a challenge run kind of way, they legitimately could be better than lightsabers). Plus, even a Guardian is going to end up absolutely rolling endgame enemies with Force Lightning, force powers are stupid powerful in this game, so build viability is only really a concern for the beginning.
EDIT: Oh, also, there's an early game conversation where you set Revan's gender and alignment, and a lot of first-time players don't catch that that's what's happening. So, just be on the lookout for that.
Oh, also, once you finish, come back and make a thread about it. I'd love more excuses to talk about Kotor2
I honestly never played with mods, but KOTOR 2 is a perfect SW RPG and I am so happy for you getting to enjoy it for the first time. Have fun and may the Force be with you