I push the brightness down and the contrast up as a rule. With sketches I'll do it twice. My procedure is to make it darker than it needs to be, fill the parts that are supposed to be light with white paint fill, colourise, then push the contrast way up (hope that makes sense). That's how I get that really bright look.
I can't get the settings on my camera right. Not to mention it seems like i always finish drawings at night. Like i probably will tonight lol. I know what you mean it just seems like my pics are too dark to begin with