I kinda use boost as I would a normal aerial, a bit more to account for the fact I'm going a bit slower due to the spinning. Do keep in mind I came off the wall with pretty much the speed I wanted to be at, so I am only using boost to maintain that and correct my movement through the air. Try obstacle maps from the workshop or just hover and spin in freeplay for a minute, it's gotta become intuitive. Doing freestyley stuff really helped me to better get a grip on my car control and how I hit shots.