I've never actually had to roll a d4 on a table. Baldur's Gate handles it for me.
There are 2 kinds of D4 dice. The result can be on the bottom or on the top of the "piramid".
...well, there are more than two kinds of d4s, but there are two popularly-styled tetrahedral d4s...
Flipping a coin two times and reading the result as binary gang. (Don't actually do this, coins aren't as fair)
They're only off by about 1% and the bias depends on which side was up, it's not that bad. I wouldn't expect most inexpensive dice to be substantially fairer than that.
I suppose it's basically flipping turned 90 degrees, so it might still be affected but which face is forward when being spun.
