How do I find the hybridisation of the orbitals of carbon in a molecule? What are hybridisation states of each carbon atom in the following compounds?


$\ce{CH2=C=O}$ 
$\ce{CH3CH=CH2}$
$\ce{(CH3)2CO}$ 
$\ce{CH2=CHCN}$ 
$\ce{C6H6}$


How do I find the hybridisation of the orbitals of the carbon atom in such compounds?
My method for finding the hybridization of the orbitals of an atom in a molecule:


Look at the molecular structure (geometry), apply the following: 


Tetrahedral: sp3
Trigonal planar: sp2
Linear: sp