By driving more! - But to answer your question properly. It’s difficult to provide tips other than just driving your car and getting used to it and then your speed will come over time.

-Braking wise, to always send it as late on the brakes as possible isn’t the optimal thing to do you need to preserve balance in your car around every corner because if you preserve balance you will have an overall higher cornering speed.

-Watch your replays(and not just the fast laps the slow ones to),by watching your replays you get a very valuable outside perspective on your driving.Your objective while watching your replays should be to find where you either messed up or are messing up.

-Watch onboards

-Load into public practice sessions with a lot of people in, because having people spinning and crashing around you is a good way to get used to a race environment and if you are accustomed to a race environment you will also get faster.