There's real potential there. I like the choice of leather armour, it fits the elves better than steel.
The face strikes me as kind of oriental, though. I like my elves with tall, narrow features, high cheekbones. A narrower nose/face, and higher cheekbones would be good IMHO.
That aside, technically this is good quality. You've got an eye for the shapes of things, particularly the armour and sword. His collar's a little shapeless, though. And i'd prefer a sabre-type sword rather than a straight blade, myself.
You need to be a bit careful about your colouring, though, there's a few places where you've gone over the lines. And the metal colouring needs work - the blade looks totally flat at the moment, when it should be broader at the back of the blade, and thin to an edge at the front. It also strikes me that the handle's at slightly the wrong angle compared to the blade.
But this is great work. With a few refinements, i think that it could be mainline quality, although obviously my opinion has little bearing there. As for UMC, I don't really know what campaigns need artwork, but your best bet is probably just to keep an eye on the
forum section, and see which threads are active. Most if not all of them will be on the lookout for artists. Shadow Master's Invasion from the Unknown strikes me as one which would probably be a good bet, as does JW's Era of Myths, particularly if you can turn your hand to spriting.