A Recipe for Drawing Lewis Structures

Determine the total number of valence electrons in the structure, adding or subtracting electrons from ions, as necessary.
Determine the atom with the lowest electronegativity (other than hydrogen), this atom is generally the central atom in the structure. Hydrogen is virtually always a terminal atom.
Distribute the other atoms around the central atom. Place an electron pair between each terminal atom and the central atom to form a single bond.
Distribute the remaining valence electrons around the terminal atoms so that each has a complete octet.
If valence electrons are still not used in the structure, place them around the central atom to complete its octet.
If, after all the valence electrons are distributed, the central atom still lacks a complete octet, transform lone pairs on a terminal atom into a multiple bond.
Check that formal charges are either zero, or are as low as possible.
Check that only "acceptable" violations of the octet rule occur in the structure.