This is (what I would consider) a GREAT powerpoint to teach your class formal commands. I wrote it while using the Avancemos 2 textbook, but I think it should be pretty compatible with any text. The first part of it is a thorough explanation of the topic, including photographs of actual signs in Puerto Rico that I saw on a trip there. There is practice, as well as further explanations of what to do with pronouns. It usually takes me more than a full class period to get through this.
Please also check out my other materials here: