i definately am not feeling the pinkish background - it doesn't match the character's feeling. should darken or saturate it more. i played around with you image real fast, hope you don't mind - it was in hopes you might like something i did.
i brought your colors closer to a monotoned pallet so they jived better, i would add some nice dashes of color here and there to make it stand out more.
i burned with a large soft-edge brush in shadow mode at a low setting (10). it really helps me push the contrast where it needs it. i really think you should push the vieny areas that have very few values - over using it will result in a bad look.
i composited a pic of stained cement over it for a quick grunge finished look. even a solid color overlayed at a light opacity will help harmonize your colors better. it isn't always a sure thing, it is good to have complimentive contrast in your colors.
i threw a sharpen filter on there.
i really like the way you rendered the form in this piece. the character looks cool.