You hear it a lot. "The secret to good climbing is footwork." along with "John Dunne was 14 stone and on-sighted 8b because he could use his feet" etc. I have been concentrating on my own footwork recently and it is paying off, I think. After getting beyond the I'm not strong enough mental block. Thinking about my feet has really helped. Also being prepared to pivot from the hips and so get my feet into places were they are more use has helped even more. I'm struggling to get the high steps that seem to be important if I want to move beyond 6b on grit. I think core strength is probably important here too. So that is being improved one unpleasant crunch at a time. Oh and I saw John Dunne at the foundry once and I was amazed how "well clad" he seemed and how good his footwork was.
Here are some other peoples thoughts on getting better with your feet:
Rock Climbing for life