Variable names should start with a small letter, must not start with a number, may only include special characters $ and _.
Writing desriptive variables names will help reduce the amount of in-code documentation required, improve readability and reduce naming conflicts. Use camelCasing (compounding multiple words together, but using a big letter to show the start of each word) where you might normally use a dash in CSS (remember, - is not valid in JS variable name).
More to come.