I can enjoy and ask? How to choose the size of game objects (the player, for example?) 32x32, 64x, 64 ...? Are there any rules or good practice for this?
I totally agree with what you are asking. This is something I've been wondering for some time now too. I mean that's great that there are those scirra tutorials about resolution, but the big problem is actually how much data you have in your game. In other words. You could have a 200x400 sized screen, but if you need to load in 8-billion animations then is sort of defeats the purpose, doesn't it?
I guess what I'm saying is that I'm trying to find a least common denominator (optimization). I've been trying this for a while: how to have a good pixel-sized screen, but also have the amount of frames of animation and background sizes not exceed the length of time it takes to load a game.