your doing great and I didn't the portal rings became a daily deviation?..erh never mind..
let's see, its a really tough call what people like to see...
you did good with the cherry sticker::http://mysticeden.deviantart.com/art/B-Gata-H-Kei-192478671
maybe make other fruit variations....
and apparently people are starting to like this -_-!http://mysticeden.deviantart.com/art/Super-Mario-World-183617494
why not combine the two and see what happens...?
also may want to be aware of artists alley's new rule!
like all professionals would say, it is based on what you think will sell and what not..
Start with the basic sets you have,
Zelda / Any nintendo character
naruto / onepiece
things that sounds interesting to other people are:
hatsune miku (vocaloid)
Hetalia characters(are they even still fresh to others?)
Kuroshitsuji (anything victorian like effect)
Maybe one of the precure series!