Tips for newborn sleep

So my newborn sleeps really good all day. But at night she won’t. Like no matter what we do she’s up and crying. The only thing that kind of works is if I hold her. But then I can’t sleep because of safety issues... but hey better than her screaming and then my husband can get a couple hours since he works. I want to establish a nighttime routine. I know she’ll probably sleep bad for a bit but Idk I just feel like it’s important. So what are your tips? We have a snoo but she’s a preemie and so she doesn’t fit yet. Also as a new mom I’m not sure how often to bathe her and what time is good to implement that. She’s on a 3 hour schedule about currently 2,5,8,11.