Trust your gut. If, when you meet with your designer (or any service professional) you don't have a good feeling, walk away. Not everyone plays nicely together and that's okay. Even if your friend had a good experience, trust your instincts if you don't feel confident about moving forward.
Be willing to give up some control. After doing your research and listening to your instincts, be ready to hand the reins at least partially over to the professional. This is their chosen field, it's what they do. And, since most service businesses are based on referrals, they really do want to give you their very best.