How to pick a surgeon for breast augmentation and tummy tuck?

I went to a consultation last week for a breast augmentation and tummy tuck. I am a 34D and the surgeon recommended between 300-350cc for my saline implant. Is this normal? & how big will I be post op? Are there any red flags I should look for? How do i ''check'' someones credentials. Is it normal to attend only one consultation and be set on a docter. Ive never done this before and im only 18. Dont want to get lead on into doing something that could ruin my life!