All you really need to do is wash them with anti-microbial soap (which most dishwashing liquids are today) and scrub them with a soft bristle tooth brush. Give them a shot with scrubbing bubbles, which has germ killing capacity.
If you are the conscientious type, you can dip them in alcohol, and let them air dry, which is deadly to cooties
If you're the nervous type, you can boil some water, then pour the boiled water on the razors to soak a little. (don't boil the razors themselves)
If you're the paranoid type, you can give them a brief soak in diluted barbicide (available at beauty supply stores).
That's really all there is to it.
if you are the obsessive compulsive type you can put them in an autoclave.