Some valuable & helpful info has already been offered, I'd like to add that art type, location, space availability, & time restrictions also come into play often. For instance, when displaying art in booths all my originals are framed & strategically placed on display easels to draw attention, but less expensive prints are displayed unframed in glass display cases. I often have a selection of frames available and sold separately. If you are displaying art on commission, ie... a restaurant, business location, etc., it should always be framed. Online sales have the most options & flexibility available, it's usually a matter of buyer/seller preferences. On some pieces I offer separate pricing for framed or unframed. However, while I do not offer frames for prints, I often offer size options which is a lot more appealing to most buyers. When doing a commission, I always defer to the clients wishes regarding both size, & frame, but I am not as flexible with pricing, payment, & shipping methods. I also do not ship out of the U.S.A. My advice is to really determine what your goals, time availability, & limits are... then move ahead in every direction that takes you there comfortably.