My 2 cents: True, Walmart is so automated that you'd be fooling
yourself if you think that someone actually looks at your print -- but
I'm really happy with the quality of Walmart's digital prints!! Here's
what I do: simple really -- do all of your own digital editing
(levels, color balance, sharpen in Lab mode, etc.) on a copy of the
original, then optimize your file to just under 3MB in size.. I shoot
in TIFF, convert to PSD, then optimize in Image Ready or Photoshop to
just under 3MB.. because it's the maximum file size that Walmart will
upload. Forget the pixel dimensions as a guideline for print size. As
long as you don't resize your file, it's already in the proper ratio
for 4x6, 5x7, 8x10.. assuming you aren't using some very strange
camera or lens that crops..
also, don't use in-camera sharpening. It's too much. I use a Coolpix
990 for almost everything, and my prints are fully equal to my Nikon
35mm film prints from Walmart. Another kudo for Walmart -- unlike most
ink-jet printers, I find that WYSIWYG -- yes, my monitor is nice, a
LaCie, calibrated with Adobe Gamma (nothing fancy), and what I see in
Photoshop before I upload the files for printing is EXACTLY what I get
back from Walmart. However they've set up their Fuji equipment,
they've got it right. I'm selling my Epson Stylus Photo 1200 ... no
use for it anymore. So, do your part, and Walmart will do theirs, and
very nicely and economically, at that.