Can anyone give me some tips on how to use feats in combat? AFAIK combat-related feats can generally be divided into three groups: Power Attack/Power Shot, Rapid Fire/Flurry, and Snipe/Critical Strike. According to the game, Power Attack/Power Shot are most effective when fighting large groups of weak enemies, like gangsters or Kath Hounds. However, I cannot find any information on the other two types of feat, aside from a big pile of stats and calculations. What is the best way to use these feats? Are they even worth using?

Generally, you pick one and max it out.

IMO: Assuming you are going to be Lightsaber wielder eventually:

Chose Flurry

Max it out, and use it in every melee/lightsaber attack.

It's the most consistently usable, and has the fewest penalties.

There is no one right answer to this.
All three feats have their uses and none is clearly better than the other two. It mostly depends on your weapons and other feats.
Power Attack, for example, reduces the chance to hit while dealing more damage. If you have increased your chance to hit with other feats/abilities, you can negate the penalty and consistently deal more damage every hit.

Yes, you can argue endlessly over the minutia. The truth is they are very close. Which is why I said pick one and Max it.

I probably should have added that If you play a weaker Dex based Jedi, then Power attack makes more sense, as the power attack damage will be more consistently ahead of an extra weak attack.

But Strength based Guardian Jedi, will be putting out close to 40 damage per hit average by end game, so they extra hit equal the BEST case bonus of Power Attack.

Though proponents of Power attack tend to think, they will always have the best case with 4 attacks/round and they will never miss. Both of which are false.

Even at level 20 having an attack miss out of your set is still common, and then power attack doesn't look so good. You get -3 to hit with PA, -1 with Flurry, so you that miss out of your set will happen more often with PA.

Also you have to always be running Master Speed for Power attack to make a case, which since it last 20 seconds and take a round to "cast", won't always be the case either.

Also if you want to do your Guardian Jump, you can't use either method of attack, which is another reason IMO to go for a strength based damage build to start with.

So Dex, go Power Attack, but really I wouldn't suggest Dex based.

Strength, it is so close it really doesn't matter, pick the one you find most fun.

IMO, I like flurry. It feels faster, you get a couple of slashes in while racking up your hits.
Power Attack pauses does one somersault, that looks like a single hit and all your hit register then. I find it annoying.

On a good damage build it is pretty much inconsequential as they will be very close and you will shredding everything.

Thanks for clearing that up. I think I'm just going to continue with my usual method of just maxing out whichever combat feats I start the game with.

A reasonable approach that saves on feats. Provided you skip upgrading the ranged version for your Jedi Characters. It's kind of a waste of feats to upgrade the ranged ones if you are going to use a lightsaber. Guns kind of suck in Kotor 1.