when playing lead place the part of your hand below the thumb on thestrings above the one you are playing. this will mute these strings. this will aslo mean you have to pick from the wrist as apposed to the elbow. the elbow is used to change which string you are picking with your wrist motion.
then with thr fretting hand place the sides of the fingers against all the strings that are below the one you are playing. this will mean that all the strings above and below the one you are playing will be muted letting only the one u want to play ring out.
best of luck