Welcome to the forums
. The best tip that I can give to a beginner when it comes to mods would be to look at all of the mod threads you've heard of and compare and contrast their features until you find one that's appealing to you.
Project Blue,
Horror Mod, and
Fenix Mod all increase your framerates and allow you to create
much larger levels over unmodded FPSC without worry (and of course they all add a large variety of new commands for you to use in your games as well).
Personally, I would recommend any of the three. I have used all of them, and they all have their own unique features, and they are all great. Though, I would suggest that you give
Fenix Mod a try before the others, since it is free.
Kravenwolf