if you're in a big city or any area where there's a lot of radio activity, it may just be something you have to deal with unfortunately. make sure you have good quality cables that are well shielded. you can shield the inside of your guitar's control cavity too if it isn't already. other than that, if you have a lot of pedals then you can take them out of the signal path one at a time, as they can often times pick up radio frequencies.