you may be right TrophyPrint, But i am not full satisfy with you answer so any one would like to tell me.
Your competitors are most probably going to optimize the same keywords you have. Anyways if not, you could "view page source" of your competitors website and look in his meta keywords tag (there are little chances his website might even have this tag since it doesn't carry anymore weight). If that doesn't work, look at his main heading (the h1 tag) his main keyword or key phrase should be in there. Also look through his content and look for words or group words that get repeated often, those are most probably his keywords or key phrases. Another good way is to simply look at his title. The title should always contain the main keywords of your web page, so if he did proper SEO, his keywords should be in his title tag.
1.Take a look at his page source 2. If you can not find the keywords there use a keyword density tool 3.Try to find out that is the most used anchor text for back links Good luck!
The free version of SEMRush will show you the top organic and ppc keywords for any competitor. Full version shows all words. Small sites may not have any data, but worth a look.