If an investment banker can't provide the following, DON'T HIRE THEM:
1. Experience and knowledge of innovative financing structures to maximize client value (by proof of past clients)
2. Direct relationships and established contacts with a breadth of private equity funds - ability to present a deal and know the funds will listen.
3. Produce an extremely high quality financial model and written report in a manner that will attract fund managers.
4. Prepare some 75% of the due diligence material material required by a fund - save the client the time and effort
And most importantly:
5. Be capable and experienced enough to negotiate the best terms for the client with the fund. Fund managers negotiate financing deals for a living, whereas most entrepreneurs negotiate a major financing once or twice in a lifetime. A good I-banker evens the scales.
Hope that helps!