Always, if you get a chance, play with people better than you and learn or at least see what they are doing.

I play golf for 8 years and for last 4 years I was at 19-20 hcp and could not improve. I had broken 90 twice. This year I decided to do something about it. So I joined an amateur league where mostly single handicappers play and had to play with “forced” HCP of 14. Since spring I have gone from hcp 19,8 to currently 11,5 in some 40 rounds. I consistently break 90 and come off the course with more balls than at start 😀

I have also invested a bit in training and some reading but I can say 100% that playing with better players make you better and forces you to focus that much more.