Like Mike said, I also have watched the Chris Olson video's about advanced F2L (and his advanced LL video is also very good). You learn from these video's but like with all new things you learn, it will take some time before you become faster with it.
I've watched those, and many other F2L tricks videos, and i don't think it's the answer for me. My F2L is pretty efficient already - I have efficient solutions to all cases, can solve at all corners equally, make use of empty slots, can avoid rotations in many cases, etc. These days it's rare that I find an F2L trick that would clearly save me significant time in a solve. I'm also happy with my LL algs and cross efficiency. My solutions are fine, it's just that I suck at doing them fast.
I get a lot of 15-16 solves and also a lot of 20-21. Sometimes it's just down to easy or hard cases, but generally if I look at the difference, it comes down to three things: composure, grips/handling, and lookahead. In a good solve, I just seem to see everything and flow through the solve with no pauses, with execution nice and smooth. In a bad solve, I lose track of pieces, catch or fumble on algs, rotate too much, rush too much, change grip too often, etc. It's those things I think I need to work on. I thought most of them would just improve with doing lots of solves, but it seems not, so my plan is to find some targeted practice techniques for them.
@Mike: I do keep track of my splits. My cross and LL are within range for a 17 second target, but my F2L and especially cross-F2L transition are not.
Then I watched a video of how to make the first layer in order to learn full CLL. That was very interesting. I might look into that some day.
Yeah I read in another thread recently that if you just make a face with no regard to layer, 2/3rds of the time it's an adjacent swap case. Therefore it makes more sense to learn EG1 before CLL. That makes sense to me and I like that kind of logic

. I might learn a few easy EG1 cases just for the adrenaline rush
