Like you said, the numbers are the MOST important part of a deal.
Every buyer is different, it is important that you learn what they're looking for in an investment and keep notes. When you find a buyer to add to your network, ask them what they are looking for and where they'd like to buy. Some buyers may like heavy rehabs in the north part of town, while others might like turnkey rentals on the south side.
I've found that my buyers really like that I handle the communication between all parties (seller, buyer, title). Buyers also like a small DD package when I offer my deals (comps, ARV, repairs, photos, tax info). Buyers love broom-swept properies after the seller vacates. It is also nice if the buyers can look at the property without the current tenants being there.