How to dress a baby for sleep

I'm a first time mom here! 😊 I am considering on buying a wearable blanket like a Woombie. But, I can't decide on how warm to dress my baby. She'll be here in August, and it'll be HOT. Do you dress your baby in a long sleeved sleep and play and then bundle him/her up in a swaddle? Does the baby wear a cap to sleep? What about short sleeved onesies? I've babysat before, and noticed that I tend to overdress my friends' babies for a nap. The kids wake up kinda sweaty. So I want to avoid that. I certainly don't want to do what my SIL did and turn the whole house to 80 degrees F during the winter so that she wouldn't have to put a blanket on her baby.