I'm not an expert, but I would highlight in any applications the fact that you've done supply to gain experience in a range of settings and have massed fabulous behaviour management skills and, if you've been with the same class for a longer-term supply before, have managed progression of learners. Talk about how working in different schools has given you excellent communication skills and make sure HTs know you by name, so you can ask for references. Sorry, you're probably already doing all this anyway. If it makes you feel better, I'm not doing supply and still haven't had any interviews. Good luck with it all.