How to get a discount when booking via OTAs?

I am planning a short trip soon, and I am using one OTA that my work colleague recommended. However, I forgot to ask her if I could get any discount or some kind of deal, and I couldn't find anything on the agency's website. So, I thought I'd ask here.

Do OTAs generally offer discounts for bookings, like codes or coupons? Even if I can't get one now, cause it's my first booking via this particular agency, how would I get one in the future? Thanks for replying.