I've tried it both ways. When I sold a few prints to begin with I marked them, erroneously, as a limited edition. I've only sold one or two more of them since so it makes the idea a bit pointless really. Now I'm just happy to sell them and don't bother. At the stage I am at I feel that editions are pretentious and don't do me any favours. I'd rather sell a few at a reasonable price. I charge £95 framed, £65 unframed and have to pay some commission to the shop/local gallery.
There are ways of doing it according to gallery/buyer principles and etiquette but the point is this - is there a demand for a) your photos, b) a number of your photos? If so, how many do you think will satisfy the demand? And how does the demand influence the price? If you are in this position then GREAT!
If, like me, you can't demonstrate a real demand then don't bother with editions and numbering. Chances are you might sell a few and 4/50 will be all that ever happens.