thank you everyone for the advice really helpful (:

I think you got your answer Yunier, but i would say just in the title and first paragrph should be ok.

I usually use a keyword in the beginning and the end of the page or post.

One is enough

In a given post I place a keyword in the first paragraph, then another close to the end of my post.
Also what I do is save the others I find in a separate file that I've created only for keywords, so I can access them for future posts.

I find concentrating on one is good but I also use others in the same post as bullet point or sub headings to paragraphs. I will map out a post with several keywords.

You'd rather write 2 posts

Focus on only one. Combining two will not give you a higher ranking.

so you wouldn't combine two different low hanging keyword phrases ? also they are both under 30 for competition ! I actually was going to do a pretty descriptive article breaking it down to the tee ! specially since the websites on the first page aren't so authoritative there was even a youtube video with less than 1000 views on the bottom of the first page.

Choose one keyword that you are targeting. Just write your article naturally and add the keyword where it sounds natural. Also make sure the keyword makes sense.