After choosing my niche and finding that my main keyword phrase is worth using. Do I use the rest of those words from the google adwords list to create my posts??? Example if my main keyword phrase was office decor and I plugged that into google adwords and it spit out a long list of relevant words like paintings, vases, and table furniture. Do I create my posts using those other words on that list??
This depends on you if other words are good to you or not.If you have content for them or you like to have such content, IMO then it will be useful. Google adwords tool shows you the synonums also for a keyword. You may try keyword phrases and not only a single keyword.