Our son's advisor was recommended by his college coach. He knew we had lots of questions and concerns and knew he would give good advice, regardless of his relationship with the coaches. Some schools have relationships with advisors.
If your son may be a potential pick, nothing wrong with having a discussion with the coach who signed him.
MidloDad,
Player can get all the "free" advice he wants. As long as there is no written agreement for representation, player can speak to whoever he wants. And any negotiations are allowed through anyone who is not a registered or license agent (eg, you can negotiate your son's bonus). The contract is a basic minor league contract, which you can familiarize yourself with before the draft. Some players do not even pick up an agent until after they have been drafted and ready to sign.
There are lots of questions that go along with the process and if player and parent are a bit overwhelmed, then seek advice.