I am sure that there are other mistakes that are important that did not make this list. Please feel free to add them in your comments!
#7 Not understanding the 'rules of engagement.' Most often the rules of engagement don't allow for on premise or direct selling/marketing. That can be difficult for companies and salespeople who are used to meeting managers. A violation can get you thrown into Vendor Prison. Not a good place to be!
#6 Non-compliance. This could rear its ugly head in many different ways; not adhering to mark-ups, pay rates, employment status of your contingent worker, documentation, etc. Excellent record keeping is mandatory. If you are not set up for this, you're going to be in trouble.
#5 On-Boarding. There are a slew of documents & processes that needs to be followed. You better understand them completely and be prepared before that first placement is made!
#4 Infrastructure. Do you have the right people; account managers & delivery teams to support the MSP/Client business? I have found that most companies don't. It's not the same business as recruiting for direct-retail.
#3 Financial impact. Most MSP programs are driven by a mark-up, have a fee (2-4%) and many require volume discounts. Have you calculated what the impact will be from an expense, revenue, margin and net income perspective? Where do you need to be in order to consider the program profitable? What is the break even? What are your time-frames?
#2 Success of a program. How are you going to measure success? What are you using; placements, revenue, gross profit, a combination? What time frames? Big mistake is not defining success!
#1 Getting on a program that you shouldn't. Getting on an MSP program for the logo is a waste of everyone's time. If you are not committed or can't support the MSP Program, be honest and live to fight another day! Target programs where you will be successful!