What to look for in a property management company?

I have seen comments in my search here but still unclear on what I should be looking for in a Property Management company.

We are in a new building of 24 units that will soon turn over from the developers management to our own association.
If we choose to hire a professional management company, what should we expect to pay in New Jersey.

We are not large enough that we will need an on-site manager but the association will want to go to the management company to arrange for maintenance and repairs and maybe accounting services.
Thanks