how do people come up with tattoo sleeves?

i want to get a tattoo sleeve, and i have been looking around on the interent for inspiration. I really like sleeves done by Nick Baxter. How do people come up with sleeves that look that good? I am not good at drawing at all, and I want a sleeve that looks similair to the other sleeves nick baxter does, I wouldnt copy any though. And I dont want a stupid one like knots or tribal, or any flash s''t