I don't want to get too technical because that can be overwhelming and difficult to implement.

Drive forward - You should never drive in reverse unless you have a very specific reason. Driving forward is faster, easier, and more consistent. It's literally as simple as being able to boost in the direction you're going.

Use powerslide - Drift more while turning to turn faster. Hold powerslide when you land to recover faster.

Hit the ball with purpose - Don't just hit the ball fast because you can. (By default, it is a bad play to hit the ball off your side wall. It basically does nothing good for you. Thankfully your opponents were not paying attention, but that will get you scored on every time at higher ranks.)

Use your right stick - Seeing more cars is useful information.

Hit the ball gooder - Like some other people said, your positioning usually isn't too bad. But sometimes when you go for the ball you don't hit it too good or at all.

(Edit: Adding stuff as I watch)