On page keywords

[saramarten]

The Analyzer approximates some of the page keyword ranking measurements search engines use, but not all. Also, different search engines use some of the measurements 

[fsdqasmia]

using 3 keywords in a single page is ok. if you are going to use more keywords in one page it should be spamming.

[Dennis Zocco]

I guess it is good  to use 3-5 keywords.

[sai krupa]

Keyword helps to get the good PR and more traffic to the websites. On-page keyword must be unique with the less searches to compete with the other websites. Based on the requirement we can add the keywords to the website.

[nexusmedia]

Try to use 2-3 keywords the most put your main or targetted keyword

[cortomalteze]

After you have chosen the keywords that describe your site and are supposedly of interest to your users, the next step is to make your site keyword-rich and to have good keyword density for your target keywords. Generally, the idea is that the higher the keyword density, the more relevant to the search string a page is. The recommended density is 3-7% for the major 2 or 3 keywords and 1-2% for minor keywords. Try some of the Keyword Density Checkers  to determine the keyword density of your website.

The next important thing about keywords is putting keywords in the right places:

- Use the keyword in the title tag at least once. Try to keep the
keyword as close to the beginning of the title tag as possible,
- Once prominently near the top of the page,
- At least 2-3 times, including variations, in the body copy on the
page, sometimes a few more if there's a lot of text content,
- At least once in the alt attribute of an image on the page. This not only helps with web search, but also image search, which can occasionally bring valuable traffic,
- Once in the URL,
- At least once in the meta description tag.