To obtain boost, simply drive over an active boost pad. There are two types of boost pads: 100% refill pads, which respawn after ten seconds, and 12% boost pads which respawn after five seconds.
To conserve boost for the aerial itself, you should speed up by accelerating the car and front-flipping to build speed.
It is important to note that you can only flip for the first 1. 5 seconds that you have been in the air. After 1. 5 seconds you will have to land completely in order to flip again. To refresh your ability to flip, you may land on any surface including the floor, walls, ceiling, or even onto the ball itself so long as all four wheels make contact with the surface.
You can slow down by releasing the accelerator, holding reverse, or power sliding. Power sliding is advantageous in that it allows you to quickly pivot to face another direction.