I won't write a whole book since I don't know where you stand. Here are and handful and they are all easy to understand and try. Many are obvious, unless of course they are not.
1) Practice and increase exit speed for the corner
preceding the longest straight as that is where you will gain the most time. And then the corner for the next longest straight and so on.
2) I watch hot laps and mark down the minimum speed used in each corner and set that as my target. Hint: you will need to brake sooner so that you can roll through the corner as you transition to the throttle. This technique will dispel the macho late-braking that tends to lower your corner speed and hence your exit speed. You are already trail braking so are on your way.
3) Search for
@Tidgney 's Bathurst video at 18:40....
https://www.gtplanet.net/forum/threads/daily-race-discussion-archive.386265/page-2460#post-13342430
I will paraphrase. You can use 100% Brake. You can use 100% throttle. You can use 100% Steering. Or you can use 30% steering and 70% of something else. You fail if you use 110%. It is not exactly correct based on my physics textbook but the mindset is 100% correct.
4) the car turns better when you ease off the throttle.
5) the
act of slowing down gets you through a corner. The deceleration from 150 kph to 130 kph shifts the weight forward and hence grip to the fronts making the turn possible. If you started at 130 kph you still need to slow down to something less to make the corner.
6) Sometimes, instead of braking, you can just lift the throttle.
Also, you can post a representative lap and ask folks to critique it. Try and include the on screen data that shows brake and throttle.
And when I started... I did not know about 1, 2, 3, 4, 5, and yep, didn't know about 6 either.