Crackles and Static: I f you have a crackling of static sound when you turn your volume or tone controls or when you flip the switches, then these controls and switches need to be cleaned. A product (used in the electronics industry) called contact cleaner is used to clean these dirty controls. You can find this at places like Radio Shack.
To use, spray the noisy part, on the inside where the working parts are, and work the switch or pot back and forth for a minute or so. Let the part sit and dry for a few minutes and then plug in the guitar and see if it still makes noise. You may need to repeat the procedure several times. Even then you may find the part is beyond repair and needs to be replaced. You may want to have your local repairperson to do this cleaning.
If you are getting noise whenever you move your guitar cable, check it for shorts or dirty contacts.
Hums and Buzzes: There are many things that can cause humming through the electric system of your guitar. Things like room lighting and appliance transformers etc., can cause problems. If you are having these kinds of troubles, try moving to a different area of room. Set up your equipment the same and see if you still have the buzz. If the problem seems to be in the guitar or amp and not caused by outside influences, then have your local repairperson take a look for you.