So I've started developing a small game using 8-bit style graphics with 16 x 16 sprites which I now feel was a mistake for scaling reasons. Is there a way to scale up from that for the purpose of getting screenshots of what's going on? How can I apply that to screen testing on mobile devices? I want to achieve a close-up style during gameplay. In what resolution should I start creating the rest of my levels? My weapon of choice is GIMP in Ubuntu, thanks in advance!

What I'd do is render the entire game at a low resolution then scale up the final result to display on screen =P (although for screenshots I'd stick to the low resolution then scale them up with an image editor or something)

Just make sure the scale amount is a multiple of 100% if you don't want it to look horrible.