Tips for printing phone cases

Hello everyone, i am looking for as much advice and tips for printing phone cases.
I am using an Ultimaker 2 and will be printing with both PLA and ABS
So how to get the best quality?
How to get the face that is touching the build-plate as smooth as possible?
How to people print phone cases that go onto curved phones, as the back isn't flat?
Best way to stick it to the build-plate when using abs?
Best way to reduce warping?
And if anyone has any experience with printing phonecases and have any information that might be of use to me please fire away!
Thank you very much
Luke

Best advice : try printing some and post some photos of your issues.

As for a smooth bottom face : no raft, well adjusted or compensated Z perpendicularity to XY plane. I use a PEI sheet on my alu bed, works wonders (except after 50 or so prints bubbles appear underneath so I need to change it).