All the brands, types of line and different lbs of line...How do I know which one to buy and use?

Species, application, and preference. Depends on the fish you are after. Where you are fishing, cover. And brand you prefer. Bass in timber, 50# and 65# Power Pro braid. Crappie under a dock, 2#-4# mono. The bigger the fish your after and the nastier the cover, the higher weight rating the line needs to be. If you are fishing heavy cover, you have to use braid. Open water, mono is fine. As far as brand goes, its just a prefence from your point of view. I used to use Berkley mono. Now I use Power Pro braid and no mono. I hate Spiderwire. I have never used flourocarbon. If I buy mono I will go back with Berkley. You will see what I mean by preference as people respond to this post.

if you would say what species you are after, and describe your tackle (i.e. spinning gear vs. baitcasting gear), type of bait, and the waters where you are fishing, we could make more specific recommendations.

I fish for Bass with an open face reel and its usually in murky water with pretty heavy cover.

The bigger the fish your after and the nastier the cover, the higher weight rating the line needs to be. If you are fishing heavy cover, you have to use braid. Like I said in my earlier post I would go with no less than 50# braid. Myself and lots of other guys here use Power Pro braid. You have to use a mono backing and tie a uni to uni knot to tie the two lines together. Put just enough mono on the spool to cover it and then fill the rest of the reel with the braid.

I would have to second the power pro recommendation as far as braided line goes, i use the 30# and 65# tests, also, unless you are fimiliar with spooling your own line, i would suggest getting it done at BPS or somewhere as they will know the correct backing to put on your reel.
As far as mono, i would aim around the 12-17# range, i use stren original but everyone will swear to their own brand.
I am not a huge fan of fluro due to the memory and lack of noticable benefits. if you want something other than mono or braid i would suggest copolymer(silver thread AN40 has never done me wrong)

i use flouro for soft plastics, braid for frogs, mono for everything else, lately been using sufix elite camo & i really like it...power pro braid, BPS flouro

15-20 Vicious Fluorocarbon line - Sensitivity, good abrasion resistance, manageable, high tensile strength, low diameter it is virtually invisible underwater and will help you detect even the lightest of bites.

Might want to try Big Game 15# or 20#.

I dont like big game line because of its diameter. I know some like it, but to me its like using a tow rope. Just my opinion.

Re: You have to use a mono backing...

What is the reason for doing that? If I decided to try braid, I would start with some nylon string, and then ty on the braided string?

I'm interested in trying braid because it seems to have a smaller diameter which would fit on my small cheap beginner spincast spools. (I'm tired of loosing lures on brush and rocks)

I have gone from using mono exclusively to using fluorocarbon on 7 out of 10 reels, there is a huge sensitivity difference when using jerkbaits and finesse fishing, I am 100% sure I can feel bites I couldn't before with mono.

I agree w/ Slide_R about Vicious fluor. I also like their mono

I have been using Vicious 15# for 4-5 months and have had no problems. I used BPS XPS Fluoro before and the Vicious seems a little better as far as memory. I also like the price of the Vicious, 3-4x less than many of the brands you see mentioned. Compare some of the Fluoro lines far as $/yd and you might be surprised.

the mono backing keeps the braid from slipping on the spool, and if the reels have a plastic spool braid can dig into it. it is recommended to use braid only on aluminum spools. i would use backing close or equal to the diameter of the braid, enough to cover atleast one layer of the spool so the braid doesnt touch it.