I was recently tested on my knowledge of basic bonding theory, and there were a few questions on the test that asked me to state what kind of hybridization was present for the central atom of a provided molecule or ion.

The first step is to construct a lewis structure, right? At that point, is your decision based solely on the electron-group geometry of the central atom, or do you have to write an orbital diagram and manipulate it? Also, how does the existence of double or triple bonds affect the process?

I would greatly appreciate any assistance. My textbook does a mediocre job of outlining the process, but I intend to look at it again and see if it makes more sense than it did last time. I didn't post this in the homework forum because it has nothing to do with homework; it's for my own knowledge.