First, take the time to master each synthesis engine. Find your best snare, your best kick, best hat, make them blend elegantly.
On the other hand, try to create very experimental percussions, just go for the weirdest and save your Sounds when they are ok. This path is important to discover what the machine can do, that you hadn’t thought of before. Think FM with LFO, percussion out of filter alone, use of noise, resample…
Another axis is to make samples better by using synthesis: try to melt both to get the best out of it.
At last, biggest problem can come from having too many sounds at once: when a beat is too crowded, you usually can’t identify easily what doesn’t work. Check this thread to get some ideas about this: