This might sound a little backwards, but my preparation for nursing is mostly normalizing it for myself. Since I'm an LC, I rarely see breastfeeding that's going well. I think, for me, it's like I'm an OB giving birth. I am doing my best to really internalize the fact that breastfeeding really is a normal natural thing to do, that I've done it successfully 3 times before, and that I need to default to trusting the process. I end up thinking every little thing is something bigger because that's what I'm surrounded by all the time. This babe has a new dad, though, and said dad is tongue tied, so I have a paranoia about that. I'm seriously considering making sure I have some sterilized blunt tipped scissors on hand.
In reality, there's no physical prep that needs to be done. The most important thing for breastfeeding is immediate and sustained skin to skin contact. Sustained skin to skin contact for the first 6 hours can make a bigger difference than anything because a neurotypical baby is going to instinctively know what to do if put in the right environment.
We plan to do skin to skin constantly for the first 8 days and then -when people start visiting more in the second week- we're still going to do a lot of skin to skin, but not constantly like for the first week. I have a talk that I give at conferences that is by Nils Bergman called "Skin to Skin Contact and Neonatal Neuroscience". It sounds like more tech than it is. It's really just a bunch of science to show professionals what moms already know. Unswaddle your baby, put him/her in a diaper on your (or your partner's) chest and cuddle under a blanket for as long and as often as possible. Many people do skin to skin for the first hour, then the baby gets weighed and swaddled and dressed and stuff and real skin to skin doesn't happen again. If we don't end up having a homebirth, SO will wear a button up shirt so he can put the baby on his chest without disrobing whenever it's his turn to hold her. The kids will hold her skin to skin and if my mom who will be here wants to hold her, she'll do it skin to skin too.
I will say that going to a LLL (or other breastfeeding support group) meeting ahead of time can make a huge huge difference. Go to as many as you possibly can! They love to see pregnant women there! Know what's normal and know who to call if you have any doubt, then don't hesitate to call. It's best to prevent problems and the earlier you fix problems, the smaller they tend to be.
Also, anyone can feel free to PM me if they have questions about breastfeeding that I might help with. There's a lot of experience and wisdom here, though, and letters after one's name really only mean that much when it's something unusual or medical, but I'm happy to help anyone if I can.