Here is a tip to give a bit more life to your safety razor. Place old jeans on a hard flat surface; then run your safety razor up the pant legs about 10-15 times quickly; then repeat running it down the pant legs. No need to press hard, just a little pressure.
Point the top of the razor in the direction you are rubbing so you do not shave the pants or try to cut them.
The threads on the jeans will fix any tiny bends in the blades and sharpen the blades. For an already dull blade, you can sharpen it by doing 50-100 swipes both ways.