The website I operate is one where the content comes from the community of members who go on it everyday. The problem i'm having is my site encompasses all human knowledge spread through ~22 categories. [tried to make it as vague as possible per forum rules]
Due to the website being so broad, I have NO IDEA which keywords to focus on. Should I just be looking at popular keywords connected to each of the 22 categories on the site? I'm so stumped. Its not as if I have a video games site and can target video games for example.
Any tip/opinions on where I should go from here? At first opening I just assumed I wouldn't so any search word targeting; but I think that is a little careless to be honest. I will give more details if asked :)
Don't look at the website being broad - look at each topic and make sure that each topic has its main keyphrases optimised. Wikipedia is a good example - zillions of topics, yet most generic searches bring a SERP with Wikipedia towards the top of the page. If you owned Wikipedia you would not bother with keyphrases such as "[something] encyclopaedia". You would simply design a great set of page templates and allocate some rules for tagging headings, inner links, alt tags etc.
Work on deep links to each topic from other authority sites for those topics.