If you have a build-a-bear store near you, they have a very tiny bat, ball and glove that I have used in newborn pics. I'd keep the backdrop simple, maybe just white. I'd let the baby in his outfit be the "focus", especially if you are using props. Will the baby be exactly 3 months, or will he be 3.5 months or more? I ask that because there is a huge difference in the likelihood of a getting a smile out of him, that even 2 weeks at that age can make. I have found that while they may be smiling all the time at their parents, when they are home and comfortable and their guard is down, they may not smile at YOU at exactly 3 months. 3.5 months, the likelihood of them smiling at any smiling face that is close to them goes way, way up. If it were my 3 month old, I'd snap them not smiling just to get SOMETHING in the metaphorical "can", and then work on the smile. Have fun!