I use the same FL mixer you do. It's how you use it though. Believe me there is a whole otherworld thats even more complicated than just "making the beat". The other half is "making the beat sound good" like i said before.
So you assign your channels in FL... now what? Well, if you have your drums tracked out, you may want to phatten them up by adding a compressor plug in to each individual channel. Adding it alone wont do shit though, you have to know what you are trying to get. Research compression.
http://www.tweakheadz.com/compressors.htm
After you've messed with that, maybe you have a string sample that sounds good but there is another instrument... say the piano... that seems to be muffling each other. First you could try panning these so they dont fight as much, then look into EQing. Just me saying "try panning or try EQing" holds no weight by itself. its up to you to research into that and learn the technics so they work for you in all of your mixes.
http://tweakheadz.com/EQ_and_the_Limits_of_Audio.html
http://tweakheadz.com/pan_control.htm
I always just experimented with panning, EQ, compression and layering. Somethings you get the hang of, somethings take much longer. It'll be easier if you buy a book that has a pro that does this for his career telling YOU how to compress, EQ and pan your tracks than figuring out all the wrong ways to do it yourself.
http://tweakheadz.com/perfect_mix.html
I dont know how long you've been doing this, but believe me all of your roads will eventually lead to mixing. If you are completely new to beat making in general, focus on your production first. It's no use trying to learn how a compressor can fatten up a track or proper panning if you dont have a coherent beat to practice on.
Hope this helps man,
Peace