To find a good manager, I would look up a real estate investment club in your area and attend the next meeting. Ask everybody you can at the meeting to give you a recommendation. There are many experienced real estate investors at those meetings and I'm sure you could get some great feedback. If you need a good resource to find a real estate investment club in your area, go to http://www.creonline.com/real-estate-clubs/.
Best of luck to you!
If you're looking for a management company I would recommend that you contact the Blue Square Realty Group in Center City Philadelphia.
I have been involved selling condos that were managed by this group recently and they were a pleasure to work with.
I hope this is helpful.