Avogadro - Conversions?

[Harlequin]

I'm having a bit of difficulty figuring out when to divide or multiply, and what numbers to use. I know to use 6.022x10^23 for atoms, molecules or formula units, and 22.4L @ STP for volume. I'm just not sure how to set up the different conversions.

What kind of equation do you use when going from atoms to grams?
Finding the number of moles in grams of a given compound?
Etc...