I haven't found anything that works real well, but I always make sure to "warm them up" with several rolls before gaming starts. I usually do this until they consistently roll mid to high teens a few times in a row. Currently, I tend to have a particular d20 for each character (I play in a couple campaigns), but I used to roll several at the beginning of a session to see which "felt good" that day.
The thing I've consistently done since high school (which was many years ago) is that I always, always set my dice out with the highest value up. This way they "get used to" having that number up.
As an aside, I haven't really had lucky and unlucky dice, but I have certainly had lucky and unlucky characters. For example, I recently had a dwarf who I don't think ever rolled inititiave over 10. Ever. He also tended to do very bad at skill checks (his first roll ever was a climb check in Sunless Citadel which he failed and almost died from). Then I've also had characters that right from rolling ability scores, just seem blessed. *shrug*