this is interesting because I've been using PS elements for several years, it came with my scanner for free.
I take my image and got to the "save for web" function, then pick the 'long side dimension' and enter a size appropriate for the site I'm at. Here it's 800 pixels. Usually I resize to 750, the short side is then automatically resized proportionately. Then I adjust the image by percentage from 100 down to 0... I usually select about 50 percent then click the resize button, and then save the image. The final result is an image of about 100 kb and about 7 - 8" on the long side.
If you have this software it's very easy to fit images to RFF and have fast upload. Don't worry about image quality too much... this is a screen you're looking at not an 8x10 wet print in a gallery.
Good luck gang!