How many keyword phrases should I target in my website? some time keywords stuffing is help in SERP thats true ?
It's about quality and consistency. Forget trying to stuff a 1000 keywords into your site. Pick 5 - 10 relevant keyword phrases and optimize for those. Google is good at picking up spam and keyword stuffing. Don't do it.
what are you doing ? you asking same question already one person can Ask this question and his post running on SEO session first page check this http://forums.digitalpoint.com/showthread.php?t=1724786 you get all ANS for your question and if any type of stuffing effect on site ranking, PR, SERP and traffic.
Batter to target 5-7 Interrelated keyword phrase from one page , target rest keywords to another pages which is relevant regard your keyword.
It really depends on your content, even you can target 100 keywords if you create content regularly. And if you are looking for some primary keywords than set 2 or 3 keywords. Also consider long tail keywords..