You need to find an agent that works with investors. Better still is one that invests themselves.
You want someone who understands investment considerations, and isn't going to freak out when you make what might be considered low ball offers. Even with bank-owned, listed properties, you still have the same considerations about what's a good deal.
You want someone who can help with comps. With an agent that's used to doing retail sales, the comps question comes down to " is this price OK" . With investment properties, you need solid justification for your ARVs in order to support the deal. That's a more complex question.
If you get pushed to sign an buyers agreement, limit it to a short time. If the relationship works out, you will continue to work together indefinitely. If not, you don't want to be stuck. Give yourself an out for properties you come up with from other routes.
I disagree with the statement " they will find the home." I don't agree with that for a retail purchase, and certainly not for an investment. Expect to look at a lot of properties. A retail buyer has a bunch of specific criteria - bedrooms, school district, yard size, whatever, and these tend to limit the houses that will work. As an investor, you're looking for any deal that makes sense financially. That may include many different properties. Find an agent that's willing to spend the time looking at many properties and making lots of offers.
Be sure the agent is OK with making multiple offers at once. Banks are slow to respond. If you do one offer at a time, and wait for a final response, you will move very slowly. If you intention is to acquire multiple properties, you'll need to be working on multiple offers at once.
Wholesaling REO's is difficult. Everyone of the bank addendums I've signed has a " this contract cannot be assigned" clause. The banks also want to control the title company used. Be sure you have a plan for dealing with this.
Jon