Don't know many one person techniques, but something you should do is this: get someone to give throwdowns to you like you normally would, but every now and then make them fake the throw (i.e. do the throwing action but hold on to the ball) and have a look at where your feet, head and hands are going just before release. You might find that you're moving your front foot across the crease, or letting your hands get away from your body and dragging you off balance before you've even seen the line of the ball. After that it's just a case of more throwdowns while concentrating on sorting those things out.
I was getting out lbw reasonably often at the start of last season, and this was the first thing we did when I went off and got specialist batting coaching. It worked too - was only out lbw one more time all season, and that was in a completely different way to the others (missed a juicy full toss from a leg spinner