Building rapport with drop shippers/wholesalers

im going to be getting into e commerce soon, drop shipping products and eventually buying wholesale quantities to fulfill different needs that i find. i have my suppliers chosen and i just need to register with them, im looking on advice on how to secure a long term relationship with them.

My phone skills are good and i am obviously polite to them, but from a business aspect i would like to know what it takes for a supplier to seriously consider me as someone they would like do to business with regularly.

I know this can depend on how much you buy and how often, is there anything else that would play into building a good rapport with your suppliers?