If you want to find low competition keywords, then I recommend using the Google Adwords Keyword Planner (Google) or the Bing Ads keyword Tool (for Bing) to find keywords and search them individually. After searching those keywords, determine their competition level based on what appears in the SERPs (Google Maps and YouTube are usually red flags for me) and then use metrics such as trust flow and citation flow (using the Moz Toolbar is another option) to quickly glance over the top 10 websites in the SERPs. If you want to be sure that you can compete for the keyword, then compare your potential competitors' websites to your own and use your own intuition to determine whether or not you can compete for that keyword.