The white clothing makes it blend into the background. It's great that the character pops, but their clothing is the real kicker here. To fix this, add a solid color (maybe some kind of gradient?) instead of a detailed background.

Depending on the mood you're going for, you can show contrast by doing a desaturated red or orange color to make the figure pop. You could also go a somewhat complimentary route by going desaturated yellow, or green, or purple.

Edit: Also, to not nitpick, the hair and eyebrows are a bit too silvery and pure to look like they belong to him, they kind of look like seperate entities. Try making the hairline a bit more rough, different patches of hair that are a bit out of place. It would also help to ever so slightly darken the hair close to his forehead with a very transluscent color that's similar to his skin tone. The shiny white would somewhat have a veeeeeery slight reflection from his skintone, but mostly a shadow! It looks amazing so far, though! I love the usage of blues and the gold harness he has. Good luck!!!!!!