Right now, I can solve a Rubik's Cube with an average of 17 - 20 seconds. Sometimes, I may get 15 or 16 second and my record is 12. I am currently using the Fridrich method and below is how long I take to complete each step.
Cross: I almost always solve the white cross, and on rare occasions I may solve the yellow cross. The cross takes me 3 - 5 seconds to solve.
F2L: I am beginning to get good with look-ahead. The F2L takes me about 8 - 10 seconds to solve.
OLL: I currently know the 2-look OLL and I use ten algorithms for it. OLL takes me 2 - 3.5 seconds to solve.
PLL: I currently know the full PLL. The recognition and execution takes me 2 seconds to complete (except for the G-Perms which take me about 3 - 4 seconds to recognize and execute).
All I have been told to this point was to either learn full OLL (which I don't want to do right now because it won't help much) or practice look-ahead. Well, I have been always practicing look-ahead over and over and my times still haven't improved at all over the past several months.
Are there any tips or things I should do to become a sub-15 cuber?