I don't think there is "a good way" since that all depends on the people. Here, like in so many places, people offer to help, but having them carry through is very hit and miss. I found one person from AQ:C who actually did read my story and gave feedback. Several got parts of my book but I only got snarky comments from one, the rest never even gave a peep.
There is a group (Wanted Ads -- same section as On Writing) devoted to finding and offering beta readings. If you haven't tried there, that is probably your best bet. Remember that you need to offer in order to receive so be prepared to do a beta reading for each one you get. I don't know of any "professional" beta readers and I would be leery of them anyway.