I have a Jackson Soloist from 86.
It has Seymour Duncan humbuckers, and theres a lot of pickup noise.

I put my hand on the killswitch or volume knob and it stops. Take it off and it resumes.

How can i stop this?

Well when my amp(a 20 year old fender twin reverb :P) hums, I turn the reverb down to 3-5 and gain to 4-7.
This is probably because my amp's ancient, but I'm getting a new one soon.