I also find to be better when I take a small break once in a while. I try not to go longer that 2 days.

I think it's essential to warm up. I do scales for no more than 10 minutes, because I get bored !

I like to jam along midi files. That way I can try new things and I seem to be a little better because I don't repeat the same thing twice. I only begin playing some songs after a good 15 minutes warm up. Try it you'll see the difference.