This tactic worked when search engines were unsophisticated and judged a keyword's relevance only by the number of times it appeared on a page. Now, most search engines know about this trick and count only the first few occurrences of a keyword or phrase. Search engines will penalize your page, by placing it further down the list or not listing it at all. Enter in a search term and it will return similar search terms that their visitors have entered to search with. It also gives the number of times that it has been entered, so you also know how popular it is.
Some people list the keywords tag before the description tag.
I haven't found any evidence that this matters too much, although it is said that keywords found nearer the beginning of the document have more importance attached to them. The number of characters allowed by the various search engines vary, and the above figures are only a general guideline. Although you are allowed anywhere up to 1,000 characters in the keyword tag, I don't recommend that you use up all 1,000 characters. As too many keywords can dilute their effectiveness. Patience Wait until your site is complete.