Are you on Google ? What's your target audience ? How many visitors you expect to get ? What are the best keywords to find your content ? How do people search ? How many people search for this word in your country ? Globally?
Those are the core questions when starting a website, updating it and writing new blogs. If you want to reach your audience you have to spend time grouping your keywords and understanding how people search. To get the idea what people search for, how do they "spell" search therms and where do they search for what you just must check those tools :
After spending some time picking your keywords, start working on your content, create it and use your selected keywords. If you don't want to spend time reading to much about SEO (Search engine optimization) or hiring SEO expert you can simply use this great SEO software to help you figure out how your site is doing in the eyes of google.