This is a very informative thread!!
I am in the early stages of recruiting JV partners for an upcoming launch / sale in the summer and so far I have been trying a shotgun approach of ocmpiling facts about our program, conversion stats, popular products, reasons to work with us, affiliate program features... it's probably a bit overkill for a first email in retrospect
I will try a softer approach of just saying hi, letting people know there will be a JV in the future and we can give them exposure in return and checking their interest I think and see if there is a better response
I'm generally finding it pretty difficult to even get any response from a most people though - clickbank vendors are pretty hard to get hold of it seems, well, in my self help niche so far anyway..