I was amazed by this article that seems to be legitimate – it was tried and tested by a talk show host Clark Howard. It explains that drying your razor blades extends shelf life – so after you shave you need to dry the razor with a towel or dip them in some alcohol or blow dry them or wrap it in a tissue until the next use. The science behind it: leaving the metal blades wet encourages the corrosion in razor blades. Oxygen in air and salt from skin are the main culprits. Easiest is to keep a small vial of oil, alcohol, or glycerine in bathroom and just keep razor there between shaves.
Here’s a video showing how the blades can be dried by rubbing them on some denim to make them last longer:
Reading the comments, I came across another trick: “I use a Sensor razor, and I've discovered that a package of disposable Sensor 3 razors is cheaper per razor than a package of Sensor Excel or even regular Sensor cartridges, and the Sensor 3 cartridge is exactly the same as the Sensor Excel cartridge except with the addition of a third blade (seriously, I can even remove them from the disposable handle and use them on my Sensor handle).”
Let me know if you experience longer lasting blades :)