What bass are you trying to fatten? Sub? I'm still working on my first track but I managed to get a nice fat sub-bass after a few hours experimenting. I just did some bare set-up in the synth and bounced it out and split the samples up on different racks, and edit them individually from there before mixing them back down together. It also helps setting the timing for each one slightly off one another to give 'em a sense of movement, maybe set each one's stereo pan off a bit.
Just feel the movements, bro. You'll get there.
