Expect the bits you thought would be hard to be a breeze and vice versa. Try to relax, enjoy it, even when sleep deprived and wiping up wee. The intensive first few weeks really are just that, it gets much easier really quickly.
Simple solution accident spray. And a ginormous roll of clean up tissue. Because even if you take them out on grass every hour or more, inevitably at some point you will be distracted by something and the floor will get washed again.
And, just like having a baby, remember the puppy hasn't read the books. Go with who they are, and work with their strengths and preferences.
Oh, and remember training is something you do several times a day, everyday. Make everything an opportunity to cement your core training needs - mine are recall, sit, wait and leave it. They can do other commands, but those 4 are the things I need them to do.