I personally despise tipping... I wish things were a set price and you didn't have to worry about whether or not you should tip someone.
My personal philosophy is that I will tip someone who provides a service for me. Hair dressers, massage therapists, nail techs, etc.
There are other situations that are questionable - for instance, my mother asked me the other day if it was wrong not to tip the caterer who lives next door. She made a couple of dishes for my mom to take somewhere else (Mom also picked them up from her house). I told her not to tip. If the caterer delivered the food to the event, set it up, and cleaned up afterward, that's a different story...
I don't know if that's "proper etiquette" but that's what I do.