Ok these are some tips which I think are good if you know how to do them to make more money out of your sales.

If you have created a psd why not code it? Quite alot of new people like a coded design.
If you can code it why not embed the design into a script such as oscommerce and sell it for twice as much as a full site?

Those techniques will make you alot more than just selling PSD's on there own, well thats my opinion on things