I always took hot showers, I couldn't live without them lol. Really hot baths area no-no and jacuzzis. I couldn't be in a hot shower to long at the end though, I always felt like I was going to pass out, I'd have to stick my head out and breath cold air for a minute. Lube up that belly after you shower even though there's no guarantee it will do anything for stretch marks. Do not stress out if you get them, it's normal.
Research anything big you plan on buying. Check different website for reviews so you don't waste your money with junk.
Don't watch those baby shows, don't read horror baby stories or research too much online. They will only make you nervous.
Do your own research on things like circumcision, breastfeeding, vaccinations, cloth diapers, epidurals/natural birth.... Don't just do what everyone else is doing or what your mother or sister did.
Eat as healthy as you can.
Be active, no marathons but don't get too lazy.
Stay home as long as you can before going to the hospital if that's where you plan to deliver. Sitting in waiting rooms and triages sucks when you're having contractions. You might have a false alarm the first time you go anyways lol. Most likely the baby will not just slide out of you in the car (well with your 1st anyways) so stay at home comfortable as long as you can stand.
Do not climb up on things.
They say to stop wearing heels once you get big.
Do leave your midwife or doctor if you are not comfortable with them, find someone you trust and like.
Don't drink too much caffeine. Try to limit it to a cup of coffee a day. If you love soda and can't give it up like I used to, switch to caffeine free and even limit that.
If you are using disposables buy a pack here and there of the bigger sizes like 3 and up. Everyone buys the tiny sizes for you.