A couple of thoughts...

- be organized and clear in your communications with JV prospects

- be mindful that it's their reputation at stake with their customers

- make sure your systems flow with no hangups (sales page loads, ordering system works, signup works, delivery works, affiliate software tracks hits and sales properly, etc)

- make sure your product does what you say it does

- make customer support a priority and do it efficiently, politely, and personably

- if your product or service works well, you will have fewer customer support issues

- thank them for helping you and be sure to return the favor by promoting quality products/services that also live up to the above points

Best,
Mark Hendricks