Kinect Star Wars

Easiest way to do this would be to select the Rookie difficulty, make sure all assists are on (should be by default) and do the first race which should only be 1 lap. Boost as soon as you start (both hands in to your chest and then push them both out in front of you, quickly.) Keep an eye on your boost meter (the green bars between the engine readouts, bottom right) and as soon as the meter is full again, boost some more. You should be able to boost several times in the first lap and this should push you easily in to the lead. You should only need to steer a little if you're going top speed when there's a tight bend but the game will do most of it for you. I would bother trying to engage the other racers just get around them and go!

Here's a little instructional video which may help.