If you have created a very detailed RFQ, you will have a handle on the complexities of implementation. This process needs to be very carefully thought out to ensure a smooth transition if you change supplier. Auditing of your potential choices is the best way forward to get the relationship onto the right footing and gain a true understanding of their capabilities.
Make sure you obtain a cost breakdown of the final quotes, including tooling, delivery and raw material costs. This will help with the ongoing management and help mitigate unfair increases from the suppliers during the course of the contract.
You might also look to put into the contract possible gain share arrangements to take into account value engineering opportunities and this will help focus on suppliers who can pro-actively assist during the product life cycle and to find a better partner.