A lot of the fun of teaching Huckleberry Finn is seeing students pick up on the universals, and apply them to their own lives. This kind of active learning should be encouraged throughout the lessons, so that students can find useful parallels between the situations in the book and the situations in their everyday lives. "What would you do," and "If you were Huck/Jim/Pap/etc." prompts should not be used sparingly.
Also, before the lesson is taught, the teacher should be up-front about the use of the word "nigger" in the book. Most students will know, but it needs to be reinforced that this is not an acceptable word to use today. Students should be told the...