RHH: How can I write good rap songs?

To days style in rap. If I write a good rhyme, I'll think in my head
that if its that easy it can't be good, but if I'm listening to a
song, say by Whiz, Ice Cube, Mac, etc, etc.. I'll hear them come up
with shit similar to what I can come up with. So I've got a bit of
writers block and need your help.