I was wondering if there are people that run business, which markets SEO services (both solely or in a set of web development services). What would you suggest to take into account before starting of such sort of business?

While having an experience in web promotion, I'm stucked with such questions as:

1. What one should promice to his clients, and what shouldn't?
2. Do you have some fixed tarrifs or you vary price for each client separately?
3. What type of reports do you make?
4. How you estimate teh effect of your services to show it to your client?
5. etc.

Since the decision is crucial, it would be proper to make a research before start.

So any help from you would be appreciated.