it used to be grounds for delisting, so you'd better check the review guidelines. Beyond that, what you need to do to get reviews is advertise here and encourage guys to review you by providing good service.
Good luck!

http://www.theeroticreview.com/discussion-boards/newbie---faq-33/provider-friends-168697
http://www.theeroticreview.com/discussion-boards/newbie---faq-33/discounts-vs-promotions-168632
http://www.theeroticreview.com/discussion-boards/newbie---faq-33/ter-ad-board-photo-board-p411-no-quid-pro-quos-168570
http://www.theeroticreview.com/discussion-boards/newbie---faq-33/re-change-nothing-168334
http://www.theeroticreview.com/discussion-boards/newbie---faq-33/re-shark-tank-lesson-168323
http://www.theeroticreview.com/discussion-boards/newbie---faq-33/shark-tank-lesson-168316
And several more ...
.
Can others help to clarify: You definitely canNOT offer a discount for "a good review." Can you offer a discount for ANY review?  
.
Anyway, if you target your ads to TER guys (TER Photo Only; TER Local Ad Boards), you are more likely to find clients who know about reviews and would be more likely to write one for you.
.
Good luck!