T = the total number of electrons we are working with for the given formula/molecule.

is the molecule charged negatively?                
  subtract the number in the charge from T
(examples...
)
you are done with calculating T.
assign an atom from the formula given to become the central atom of the skeleton
(how do I do that?)
continue
  add the number in the charge to T
(examples...)
             
               
  you are done with calculating T.
             
               
  assign an atom from the formula given to become the central atom of the skeleton
(how do I do that?)
             
               
  continue