Generally, search engines first crawl your URL, then the HTML text. It considers the first text it locates as most important. Hence, the title is the first line it will encounter. This should contain the keyword.
The ‘keywords tag’ is not believed to be used by many search engines any longer. But no harm using HTML tags, some engines may use the tag or it could be reintroduced.
Google recognizes between 3 and 7 repetitions to be a sound figure for keywords. More than 10 can be a disqualification. Packing keywords no longer helps, present day spiders are intelligent they look for common usage of language. ‘Packing’ worked earlier it doesn’t now.
There has to be one keyword per page, with as many repetitions as reasonable.
Spread your keyword through the page, don’t bunch them up in the first few paragraphs. We don’t know how an engine ranks a page, it could well use an algorithm which looks for even spacing or occurrences through the text. For example we don’t know how Google sets up a Page Rank with respect to the spacing of keywords in the text.
The other point is the keywords should read naturally in the text. This has nothing to do with the search engines but plain and simple readability.
Don’t be an idiot and pull them out of your head. A lot of people ‘project’ what people are searching for and create key words.
There is a method involved in creating keywords. Sorry, you’ll have to get someone with knowledge of search engines to do it for you.
Certain sites will return a whole lot of keywords surrounding your topic. Once that is done you can choose your keywords.
Here is an example. You are doing a site on tourism in Athens. Don’t create ‘Hotel Athens’ or ‘Hotels Athens’ Your SEO friend will tell you the keyword is ‘Athens Hotels’.
Don’t make it ‘Athens Hotel’ thinking that the search engine will anyway find ‘Athens Hotels’ . Search engines look for perfect matches and give priority to those searches.
Keyword driven website
Once you have your keywords create articles based on those keywords. Then when you are putting the site together you can create some articles which are informative and not driven by keywords generated from the list the search engines throw up.