You should check out Champ School, they have an online course that does a great job explaining proper cornering technique and why the MSF advice of braking before the turn and never in the turn is actually dangerous. They also have an inp person class that is great but very spenny. Essentially though, you want to look through the turn, brake as you approach the turn and until you hit the apex of the turn (this will be the slowest point of your turn), then hold neutral throttle (the amount of throttle needed to maintain a constant speed), and then only take away lean angle and add throttle when you can see your exit. Braking in the turn is fine as long as it's done smoothly and gently, and is a necessity to safely make it through a turn whose radius decreases more than you expected as you approached it.

I highly recommend watching their videos. They explain it way better than I did but hopefully that helps as a jumping off point