Add “keyword” to my website, then when I search for “keyword” using Google, my website will appear
That would be very nice, wouldn’t it? However, a moments thought will tell you that one web page with one particular keyword will be completing with thousands (or 10s or 100s of thousands) of similar pages hoping to be found via the same keyword. Not all of them are going to show on page 1 of Google when that keyword is typed in. The careful selection of keywords to avoid this situation is a part of the SEO (search engine optimisation) process.
The more often a keyword appears on a website, the better
No! This is called keyword stuffing and is frowned upon by search engines. It could cause your website to be banned by the search engines. Stick to well-written descriptive text.
Keyword Meta Tags will increase your search engine rankings
No! Google ignores these. However, still put them on your webpages as some search engines do use them. No reason not to.
Have one keyword per website page.
Not quite! Have a main keyword per page, but include some secondary ones too.
Website SEO only needs to be done once.
No! The world changes all the time and so does language and hence the search phrases that people use.
Website SEO needs to be reviewed on a regular basis and tweaked as required.
Trading links helps to boost rankings.
No! Large scale linking strategies are frowned upon by most search engines, and especially when the linking websites are seen to be unrelated. Non-useful links are easily identified and then discounted by search engines.
My home page will always rank highest so I should concentrate my SEO here.
No! This seems to be true, but its not. A page is a page. Optimise each page individually and with equal care.