I dont think there is really anything that you could do to prepare them, if this is the way they are then its it. I was told it just makes it a bit harder for them to learn but definetly doesnt mean you cant feed. After all its not the nipple that gets fed from, its the whole aerola.

I don't have flat nipples but when mine extend they do so at an angle, which makes it really easy for bad attachment to do damage fast. Even an lc told me that I was doing it wrong because of the way they looked after I took DD1 off, I got heaps of damage with her until we got it right. With DD2 I fast realised that it was her doing this to me, and that the shape was natural and it was actually her doing strange things with her tongue that was causing the pain. Even when I pump I can see them do it.