I concur with Mr Bliele..
I dont have an artistic bone in my body, but i engraver as much as possible in the beginning to learn how to hold the graver, learn what it wants from me.. the technical merit, which I put to use in my jewellery setting work, but to be honest, because I dont have the ability to draw and imagine up art, I find myself sitting in front of the ball looking for inspiration and finding none.. so i revert back to looking on the web for designs and transfer them for fun..
I have made peace with the fact that I will never be a "real" engraver but the tool still has a MASSIVE vital role to me.
HOWEVER
if you are not artistic naturally, dont despair, transfer systems are pretty good and designs on the web are PLENTYFULL. even if you invest in a dirt cheap co2 laser system ($900/ebay) to layout over uneven surfaces you can still do a good job.
I am not a great jeweller either but what I have found is that when you copy often enough you develop muscle memory and willl develop your own style.
Best of luck with it all
regards
Chris