Briggs is VER good at leave it. I use it for almost everything...if there is another dog that she's pulling towards, food on the table, poop, Connor, a squirrel...it works for almost everything!!
All I did was whenever she would move towards something that she was interested it I would make a loud noise - like a clap or something - and say "LEAVE IT" pretty loud. It would startle her and she would stop what she was doing, then PRAISE like CRAZY. That's it.
A book that I have says if you're having trouble with that and there something that they just won't leave pop a balloon in their face (
) and it will startle them, then tape balloons to it. I don't think that's very nice, but a last resort I guess. I have been comtemplating doing it to a houseplant that Briggs constantly gets at...