Sorry, sometimes I can be a little punny :D
In my fave eyeliners post, I mentioned my sad, over-sharpened, very soft, still-blunt eyeliner pencil that I had to stop using because it wouldn't sharpen properly without the tip breaking off. After seeing a tip online, I decided give sharpening one more go and stuck the pencil in the freezer for about an hour. Now, the tip I read about mentioned using the fridge, but I was feeling impatient :P Once I took it out, I let it sit for a few minutes and then slowly, gingerly began to sharpen it with my NYC sharpener and Voila!! I, once again, have a fully functional, albeit tiny, black eyeliner pencil :)
Give this tip a try and let me in on one of yours!