Rubywigned,
I was in the same boat as you...till about 3am this morning. I stink at UB2...I was much better at UB1.
Anyways, at 3am is when I realized that if I arc my arrows, and have the arrows hit the target as they're descending, it makes the game a lot easier.
...Well, it makes hitting the balloons and the target a lot easier.
So after putting in about 2 some hours practice, I got luck with a red and yellow balloon in the same shot, hit the target and got about 70 points. A few rounds later, I got a red balloon.
I wound up with 119 some points and got the avatar
.
A way to get the 15, I've noticed, is to not raise or lower the arrow at all, and shoot it at 50-60% power. If it's close it should give you some points. This teaches you the arc thingie...and it's pretty easy to get the hang of it from there!
MayEdit: New thread - Click