I find the "low-slung" position works for me. It doesn't help my finger-picking much, but it allows my chest to expand for singing. If I have the guitar right up high, it gets in the way of my breathing. Obviously not right down "Slash" style, but fairly low.

Les B (and others), I've recently worked out a way of helping to lock the guitar in place, if the strap goes from a strap button to the guitar neck. Get a very thin strap (a couple of bootlaces does well) and a small piece of tubing the same length as the width of your main strap (and about 1cm diameter). Put one lace through the tube, round the strap, through the tube again and then tie the ends together, so that the tube is tied onto the strap (above the strap, not underneath it) but is free to slide up and down. Then tie another lace from the strap button to the second lace, so that it crosses the face of the guitar. This pulls in exactly the right way to stop the guitar swinging round. Also, by altering the length of the lace, you can make the guitar "kick out" more or less (as per MichaelAnthony's last post), which angles the face of the guitar up to make it easier to fingerpick. The tube isn't 100% essential, but it allows the lace to slide into position more easily, and stops the main strap from getting creased up.

I invented this as a way of keeping my Regal resonator in place, for exactly the reasons LesB says. I believe this is my "invention", so let me know if it works for you and I can adjust it if you've got any suggestions. If this is already on sale anywhere or has been done previously, let me know; if not, I plan on proposing this to Elderly and seeing if they want to work on it. If they want to run with it, you may be able to buy this off the shelf instead of having to make it yourself. :-)

Graham;