Hi,

The best preparation goes on between your ears......seriously. It can be really stressful thinking about breastfeeding again, expecially when it didn't work out the way you hoped it would the first time around.
To a baby, their mum's nipples are perfect. The first hour or so after birth is a special time. If a baby is born normally and unmedicated then he will "imprint" his own mothers nipples. That's why we try to leave mothers and babies undisturbed at this time.
It can be hard to define *flattish*. Sometimes I have heard mothers say that a HP has called their nipples "flat" - when to me they look completely normal. Sometimes, when the milk comes in, and the breasts are very tight and full, the nipple can flatten out, and many mothers find it helpful to express a little off, to soften their breasts.
For my money, the best preparation would be to attend an ABA Breastfeeding Education Class.
Regards
Barb