This article is very short, and there is not much to summarize. The article can essentially be broken down into 2 parts. The first part lets the reader know what signs and symptoms to look out for to get early identification of possible cancers. The second part is a list of things you can do to reduce your risk factors.
It is up to you to determine whether or not you find the list useful for identifying ways to reduce cancer risks. Personally, I don't find it that useful. I teach high school health classes, and the list does not contain any new information for me. On the other hand, I could say that I find it useful because the list is relatively short. It is only 10 items, and the list comes from a very reputable source. The other part that I find useful is that the list explains itself. It doesn't say things like "don't drink alcohol and never expose your skin to the sun." The author realizes that people are likely going to drink alcohol, so the author gives a recommended average amount to consume. The author uses this tactic with food consumption as well. The list starts by saying what not to eat, and follows that up with information about what you should be eating instead of harmful foods.
As for whether or not there are other ways to reduce cancer risk, the answer is yes. This Harvard article is hardly comprehensive. For example, it doesn't talk about getting vaccinated against HPV.