ok first off I'd advise you to not follow everything your hear about dnb producing, because I've heard some pretty bland drum n bass out there, all made by following step after step...
I'd advise you to start making your own samples. You can create a very good kick even out of the default club kick in FL studio. Generally you want your samples to be rich frequency wise and pretty punchy. A good tip for snares is to boost around 200hz, that's the initial "pop" to the snare. The thing that is different in drum n bass is that the snare should hold enough power to substitute for the lack of a kick. You don't want your snare as deep as your kick, but if you notice in other genres such as house and techno you've got kicks and claps and snares all hitting at the same time.
eh I'd write more but i'm too damn lazy... just check out the tutorials in my sig. those should help out a bit