I usually use only the keyword that I'm targeting and maybe one or two more. Searchengines don't use it as much as the past. Besides you can only target so many keywords per page. If you put to many irrelevant keywords it might hurt more than help.
I meant several keywords/keyword phrases for each individual page, but it seems like the poster meant for the entire site. JMO but I'd do it individually
The amount I use depends on the post. I usually aim for somewhere in the 4-7 range. However, many search engines (Google) no longer use the meta keywords in their rankings. You can check out this YouTube video for more info: http://www.youtube.com/watch?v=jK7IPbnmvVU&feature=player_embedded
typically google frowns on anything over 10 from what I can gather right now ... Just use keywords that are in your post and don't try to oversell it to google... A few targeted are better than a ton of irrelivent keywords.
Like most other replies said, you should focus on a handful of keywords. I generally stick with 2-5 keywords per post or page. @jjwright85 - Thanks for the youtube video link!
I make sure that the keywords in the TITLE tag are covered in the Keywords tags of All In One SEO for good SEO.
No, matter where ever you use either in All in One SEO or some where else, keyword is same thing every where, but I think no one can give exact numbers every one has its own practice. As, my keywords vary in every post / page by considering my target keywords and keyword density.
There is no exact number, but I'd keep it to a minimum. Definitely single digits. Honestly, in most cases if you shouldn't need more than 5
I am using all ine seo plugin and i try to put 5-6 keywords in the title and description of that plugin , but i think you should create manually back links for better SERP.