First: It would be wise to set up a review station in your office. The station should consist of an iPad or computer, light refreshments, a framed letter requesting reviews and instructions on how to post them (it should be hand signed by each employee) and it should be an attention grabber. When your residents stop by to pay rent, retrieve packages and etc ask them to post a review. You can even ask your prospects to submit a review upon completion of a tour.
Second: You should instruct your maintenance staff to leave a note behind upon completion of every work order. That note should include his or her name and a request for an online review.
People love to know that their opinions matter. You will find that you will get a great response simply just by asking!
Congratulations on making big changes on your property and good luck on your future success!