This is a brilliant and simple overview of some common and simple guidelines or rules for writing. I think it will help writers be better writers. I work in the area of language teaching so a lot of my students are not native English speakers and the ideas here can help them a lot. For a non-native speaker of English they should be quite literate in order to gain a lot as discussing the meta-linguistics of the language (and the art of composition) requires considerable skill.
For a native English speaker this may be a easy to follow reference for Jr High and High School aged children/adolescents. And let's face it - it can be a good review for anyone. I have written a lot on the past and instruct research courses at the college level and still like to see literature on this area. I guess considering my job I need to - or should have such a desire. I do.