My main feature of the website was to let users upload their own postcards, or of the postcards they found or anything else.
So I used the plug-in FreeForm which was a nice easy form and simple that could allow file uploads and the ability to email that form to a dedicated email address. FreeForm can be downloaded from http://www.solspace.com/software/detail/freeform/
I amended the fields of the form through the plug-in control panel, then added my code into my upload page. The one thing I found difficult was that FreeForm automatically uses CAPTCHA, and this caused some difficulties, so I just removed that code. However it does make it less secure and more open to spam.