I use FL and love it. Dont even want to move onto another program. Not because I think they're inferior, far from it, simply because I found FL real easy to get into and dont see the point in learning the ins and outs of something else, when I can do everything I want on FL!
The basic samples you get in FL are pretty "Waff", so you may wanna branch out and get yourself some sample packs, there's alot of links around here where you can get some free shit.
Also, vst's are the way forward! Basically, a VST is a software plugin synthesizer that you can use to create various sounds from bass to piano to anything else you can think of. Most of them come with preset sounds you can use, until you get the hang of how they work, and start creating your own sounds. Beware though, most of the real good ones do cost a fair bit, you can probably find cracked versions around if you hunt hard enough but most of us here arent into hacked software, and it's frowned upon to speak about it, so thats enough on that subject. Some that I use which I find great are : anything by Rob Papen ( Predator, blue, albino ) z3ta+, junglist, legacy cell. Also, one that is spoken of loads is called Massive. Unfortunately I cant use it because it crashes my PC (who knows why???).
Also, go and search around on youtube, just type in FL STUDIO......seriously, there's hundreds of tutorials on there! And dont hesitate to ask around here, theres plenty of peeps happy to help, me included.