Not wanting to over simplify, but I think there is a formula and it has to be put into practice.
1. The most important thing is a good sounding bagpipe. You can improve your playing by 100%, but play on a bad instrument and it still sounds bad! Get someone with an instrument you like the sound of to look at your pipes, make sure they are always clean and maintained in tip top condition and spend some money on reeds, a chanter, whatever is required. You can get away with a lot if you have a nice sounding pipe. There are a lot of tips in "The Complete Pipers Handbook".
2. The next step is to establish a system of scalic exercises, there are some posted on the School of Piping website. These should be repeated to build strength of technique and stamina. Incorporate this into a solid and regular practice regime. Exercises, tune break-up (with a lot of attention to detail), playing on pipes.
3. Lessons concentrating on musicality are a great idea. Try to fix the technical issues before the lessons so you can concentrate on things you need to learn, not covering issues that you could have fixed yourself.
4. Play pipes like you are performing. Establish tuning times, how long it takes to settle the instrument and then play your contest pieces like you are performing. This will train your mind and teach you what you need to know about preparing your instrument.
I hope this helps a little toward steering those who wish to improve their playing. I am sure there are those who can add furthur suggestions?