A quick way to get students to understand document analysis, especially primary sources, is to use the SOAPSTone method.
Of course, you can Google this technique and come up with lots of varying ways to use it, but I decided to put mine out there for people who might want a quick "alternative" to something they might already be using.
I used this as a quick introduction to the technique for my APUSH class and as a reminder of how to approach difficult documents. I used the worksheet for about a week in class as a way to keep my students focused on what was important when reading primary sources.
The worksheet can be duplicated over and over for multiple sources so it makes for an easy handout or just something you keep in a folder so students can grab additional copies as they need them.