Well, you got the star trails part down pat. Now comes the selection of the foreground to complement your beautiful sky image. The tree's not bad, but it's not "stellar" (pardon the pun) either. There are two places of interest in the image: the celestial pole and the tree, and the position you placed the tree in the image tends to crowd the pole center. If the tree was somewhat more to the side I'd think the image would be even better. Besides the composition issue, there is also the question of how much additional light the tree needs (or doesn't) so that it stands out in the image.