When an expectant mother is well prepared for labor, she is better able to cope with the unpredictability and pain it may bring. If she understands what is happening in her body and why everything that is happening is okay, she will be able to accept and handle everything just fine. This results in her being less tense and better cope with the pain.
This also applies to breastfeeding. Knowing what to expect makes breastfeeding more likely to succeed.
In addition, you may also want to prepare for post-natal care. This will also aid in expectation management.
There is plenty of reading material available. Following a pregnancy course may also be a good addition. On top, there are information sessions that can be attended.