I usually buy cheap razors like the one in the picture below. However because they are so cheap, they only last a couple uses a piece before becoming pretty much useless and I have to use a new one.
I've tried using my older, less sharp razors to remove the majority of the hair and then get the remaining stubble that it leaves with a newer, sharp one which helps a little, but my razors are still going dull too fast.
What else can I do to keep my razors sharper for a longer period of time?