My biggest advice...

1) Buy a dress that has flow to it. The skin tight Amazon dresses do not photograph as well and they show every single flaw. Movement in the dress makes such a difference and it's way more comfortable.

2) Earth tones and neutrals work best. Think rust, moss, terracotta etc.

3) Adding a wide brim hat can be a cute accessory.

4) If you don't feel confident doing your own hair and makeup, seek out a professional.

5) I absolutely love Balticborn.com and Pinkblushmaternity.com for dresses. Check them out.

I don't have a ton of tips because at the end of the day, it is YOUR session. You will look beautiful, regardless :) Those are just some things I've picked up on that can enhance your session.