Alright, This is no easy task to put into words on paper and it may take a few trys and some questions and comments from you guys to get it right.
Braking is an extremely important part of getting around a track quickly and safely. Obviously, if you aren't braking to your optimum your lap times will suffer.
It is also important to remember that you are either on the gas or on the brakes. No coasting into the corners.
A few people do not understand about where the apex is....I believe the apex is the section of the corner that you pivot the bike most dramatically to change your direction. This is something that takes a while to get the hang of. If you are riding with roadrace lines, they will be different to what I teach at my schools...I teach what I consider to be SM lines. I try to maximize the straightaway by spending less time turning. This is done by pushing the bike down at the apex and getting the bike to pivot down towards the next straightaway. Line selection is extremely important...we all run on different types of tracks. Some are on Go-Kart tracks and sometimes we are on larger tracks and even road courses. Your line selection will affect your pivot/apex point and also your braking.
This is what makes it difficult to talk about braking in such detail....every corner and every track is different and because each corner is different...different braking methods will apply. So, with this in mind I am going to keep my post in-line with a typical SM track. (go-kart or smaller track)
You must brake all the way to the apex. I see too many people finish their braking too early and then coast right past their apex and exit the corner wide. So you first brake hard in a straight line. As you reach your turn in point that will direct you torwards your apex start applying a little more rear brake (not more than front, but just more than previously) This will allow the back end to come around slightly. This will help in the rotation of the bike. At this point you then transition to trail braking. This is the last section of braking but is extremely important as this helps maintain the balance of the bike. So really, I am breaking Braking down into three sections, First is your intitial hard braking zone. Second is your turn-in point toward your apex and finally is your trail braking to the apex.
Your intial hard braking zone..I like to try to keep the bike straight. And remember, just like throttle control...It is extremely important to keep the balance of the bike as correct as possible. This is done by squeezing the brake lever/petal instead of stabbing it. You need to put the brakes on in a quick but proggresive manner. This will help keep the balance of the bike right and make it easier to hit your mark each time. I use both my front and rear brake during this part of my braking, but for sure the most is up front.
Turn-in point...I like to make a u-shaped entrance to the corner. Do not dart towards the inside...this will make you apex late and exit the corner wide. The guy behind you will use this opportunity to set up a pass. As you start your turn-in increase the amount of rear brake slightly. This will help float the back end out and set you up better for the corner. Once you complete you turn-in you can ease off the rear brake a bit...Get the bike back in-line to drive into the apex...
At This point you are still using the brakes slightly (trail braking) all the way to the apex. Once you hit the apex.....roll on the throttle. You are no longer on the brakes...so you need to be on the throttle maintaining the balance of the bike.