I thought I was an ok surfer until I went for a weekend of surf coaching with a level 3 instructor........ He was forensic with his attention to detail and over the course of a few hours really sorted out some bad habits I had. These bad habits were seriously holding me back so sorting these out resulted in a huge improvement. Rest of the weekend was all about quality/length/speed of ride and having sorted out the niggling little habits, I was really working the waves in a way I have never done.
In short, go get some coaching if you feel your surfing has hit a brick wall. Could be the best money you ever spend. Ever!