@ Horseradish, I think the lines on the character's body is the manga's artist way of showing shadows..??

I agree with them though. I recommend taking off the grain filter from the water, it doesn't match the style compared to the vector. Try maybe putting just one smaller Blur filter on the vector, to soften him up a bit. The big X is bad quality, try just typing it on bigger size. The white background needs to be filled with something. Maybe you can try to fill it in with some clouds or a far away beach scene. There should be some tutorials on Deviantart.com. Lookin good so far, can't wait to see it done!