Comfy and cozy is the goal!  

A plain white onesie for baby is always our choice for Fresh 48 sessions.
It translates well into any future milestone sessions you may book to further document your baby's first year.  By having your newborn wear a onesie it allows for their toes, legs, and arms to be captured as well!
 
We also suggest having a couple of wraps or blankets on hand.
It allows for us to loosely swaddle baby as well as use it to put in the bottom of the hospital bassinet. 

However I have the following suggestions that would also work beautifully!