if you are getting a contract from a larger group (ie: >4 doctors), you will have NO negotiating power whatsoever UNLESS they are completely DESPERATE - and then you have to ask yourself why you want to work for desperate people...
if you are a superstar, who will be bringing in tons of patients because of your reputation or you have certain skills at doing something they don't already do, like develop a Stim program or whatever, then you have a bit more leverage
go over the contract first and look at things that are important to change... then have the lawyer look at it
in my experience, most contract lawyers will fuss over small details over and over again - and before you know it, you owe them for 180 billable hours for making petty changes back and forth...
probably better to have us review the issues for free and that will give you guidance that lawyers can't...
and also remember that the contract is useless if everything hits the fan, because you can sue them and they can sue you for all kinds of crazy/twisted reasons.