How many keywords is good and how many too many

Hello, I'm new to seo and was wondering how many key words I should have in my meta tag and what are the consequences of having too many?

Thanks

Google doesn't use the keyword meta-tag for ranking, but other search engines do, so its worth taking a few seconds to set it up.

In the meta-tag, I put a maximum of 10 keywords. Don't repeat keywords, or words more than twice. List in order of importance. Comma separate values (keyword 1,keyword 2,keyword three,etc)

You only want to optimize each page for 2-3 keywords, unless the competition is really low for those keywords.

Worry about the other on page factors. Title tag, description meta tag, h1 and other H tags. Those are the big on page factors, that will make the biggest difference.

Good luck.

Thanks a lot and will take the header tag suggestion as I haven't really looked into that!
Thanks again.

EDIT: Another question, my current headers are pretty short, around 3-4 words, should I try to make them longer?

yes header will help to realize search engines what is theme of your website

Moreover try to write website content related to header meta title,description and tags