Salary (Base and Commission) for Account Executive for Document Legal Support

I am considering a position with a firm that provides document management services consisting of forensics, electronic discovery, online repository, and consulting services. I have experience on the technical support/training side of this type of service but not on sales. This company is willing to take a chance on my jumping to the other side. I need to get back to them with what I feel would be a fair base salary while during training. After I become more comfortable as well as knowledgeable about their services and secure my first contract, I would then need to renegotiate my base pay and commission. I just have no idea where to start and could use some advise. I would appreciate your advise and any pointers you can share.