What are good examples of key words for search optimizing?

On a website providing used car parts and accessories what would be some key words for search-ability? The items for sale are categorized so I don't understand which would be best. For example: transmissions (category) 1999 Alero 5 speed manual, 2007 automatic Toyota Camry etc. Would you use the types of vehicles for keywords? I am lost. I have never done web design but I am newly employed with a company that is more lost than I seem to be. Help Me Please!