I mix a dab of neosporin with almond oil and massage it into freshly shaved skin. This works wonders for preventing razor burn. I mainly use it in the bikini area which tends to be the most sensitive for me and susceptible to the worst razor bumps. As long as I use the combo, there are no bumps even if I have noticed little blood drops while shaving.
I quit shaving for years because of razor burn. When I started using colloidal silver, I found that spraying a mist on my face and neck directly after shaving stops razor burn before it even starts. I have been doing this for maybe 12 years and it never fails, no razor burn at all in that period.