How many key phrases should i optimize for my website ?

[Only]

Ideally,

[409]

I think you should focus on optimizing every single page. While there are no standard answers, I focus each page on one to three keywords. Some do it with ten but I feel more comfortable with a smaller number. Hope that helps.

[Rohit J]

Could you please provide your website URL?

[Daniel M]

There is no specific number. You can have a single web page ranking on page 1 for more than 10 keywords as well.
It all depends how are you doing your campaign.
If you are writing the copy for a page I would suggest to go after 3-4 main keywords. Do a research for longer tailed keywords using these and implement them in your copy.