I dunno. What is best? Why would you have a domain with no idea what keywords users are searching to find related materials. Do what eveyrone does. Load an analytics program. Search your competition. Use online Keyword Tools. And figure out a plan for what your customers want.
You should use a good and recommended free keyword tool. i use the one which you can find out here..http://www.serpanalytics.com/tools/top_keywords