I have my postcards back from printer and ready to mail.A few things to remember as you mail your postcards:
Try to mail out quarterly- to keep your client refreshed on your new work.
Mail to art directors and editors.
Make sure your contact information is on front and large enough to be seen from several feet. (since many directors will post on bulletin boards)
Have information and contact information on back of card also.
Leave room for addressee.
Have proper postage.
Here is an excellent article by Art Director, Giuseppe Castellano on Post Card worthly-ness. And how art directors really, yes really- look at your promo postcards-