I will take an educated guess based on what I have learnt. Say your URL is free-online-roulette.html . Set your page title to Free Online Roulette deriving phrases/ keywords just from the page title. I would try the following:
Free online roulette, online roulette, free roulette, roulette,
Not sure for the last one “roulette” it maybe classified as a keyword repeat. One is a keyword phrase the other is a keyword. There are many SEO programs that will tell you whether or not there is a problem with you keywords. The one I consider to be the best is WEBCEO. The best thing about this program there is a free edition. Takes a while to master but in the long run well worth downloading.
If you use the title Free Online Roulette make sure the content supports that title.
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