Use keyword suggestion tool and select the best keywords that is not too competitive but has high search volume.
Sex, porn, alcohol and other vices are always good keywords. Lots of competition, but many 'vices' terms occupy the top 100-500 most searched keywords.
The best keywords to try and rank for are those that are searched for at least 5,000 times a month or more and have search results of less than 2million. It is getting harder to find keywords like that but would be relatively easy to rank for and will provide traffic.