1. Keywords in title tag
This is one of the most important places to have a keyword because what is written inside the title tag shows in search results as your page title. The title tag must be short (6 or 7 words at most) and the the keyword must be near the beginning.
2. Keywords in URL
Keywords in URLs help a lot – e.g. – http://domainname.com/seo-services.html, where “SEO services” is the keyword phrase you attempt to rank well for. But if you don’t have the keywords in other parts of the document, don’t rely on having them in the URL.
3. Keyword density in document text
Another very important factor you need to check. 3-7 % for major keywords is best, 1-2 for minor. Keyword density of over 10% is suspicious and looks more like keyword stuffing, than a naturally written text.
4. Keywords in anchor text
Also very important, especially for the anchor text of inbound links, because if you have the keyword in the anchor text in a link from another site, this is regarded as getting a vote from this site not only about your site in general, but about the keyword in particular.
5. Keywords in headings (H1, H2, etc. tags)
One more place where keywords count a lot. But beware that your page has actual text about the particular keyword.
6. Keywords in the beginning of a document
Also counts, though not as much as anchor text, title tag or headings. However, have in mind that the beginning of a document does not necessarily mean the first paragraph – for instance if you use tables, the first paragraph of text might be in the second half of the table.
7. Keywords in alt tags
Spiders don’t read images but they do read their textual descriptions in the alt tag, so if you have images on your page, fill in the alt tag with some keywords about them.
8. Keywords in metatags
Less and less important, especially for Google. Yahoo! and MSN still rely on them, so if you are optimizing for Yahoo! or MSN, fill these tags properly. In any case, filling these tags properly will not hurt, so do it.
9. Keyword proximity
Keyword proximity measures how close in the text the keywords are. It is best if they are immediately one after the other (e.g. “dog food”), with no other words between them. For instance, if you have “dog” in the first paragraph and “food” in the third paragraph, this also counts but not as much as having the phrase “dog food” without any other words in between. Keyword proximity is applicable for keyword phrases that consist of 2 or more words.
10. Keyword phrases
In addition to keywords, you can optimize for keyword phrases that consist of several words – e.g. “SEO services”. It is best when the keyword phrases you optimize for are popular ones, so you can get a lot of exact matches of the search string but sometimes it makes sense to optimize for 2 or 3 separate keywords (“SEO” and “services”) than for one phrase that might occasionally get an exact match.
11. Secondary keywords
Optimizing for secondary keywords can be a golden mine because when everybody else is optimizing for the most popular keywords, there will be less competition (and probably more hits) for pages that are optimized for the minor words. For instance, “real estate new jersey” might have thousand times less hits than “real estate” only but if you are operating in New Jersey, you will get less but considerably better targeted traffic.
12. Keyword stemming
For English this is not so much of a factor because words that stem from the same root (e.g. dog, dogs, doggy, etc.) are considered related and if you have “dog” on your page, you will get hits for “dogs” and “doggy” as well, but for other languages keywords stemming could be an issue because different words that stem from the same root are considered as not related and you might need to optimize for all of them.
Optimizing for synonyms of the target keywords, in addition to the main keywords. This is good for sites in English, for which search engines are smart enough to use synonyms as well, when ranking sites but for many other languages synonyms are not taken into account, when calculating rankings and relevancy.
14. Keyword Mistypes
Spelling errors are very frequent and if you know that your target keywords have popular misspellings or alternative spellings (i.e. Christmas and Xmas), you might be tempted to optimize for them. Yes, this might get you some more traffic but having spelling mistakes on your site does not make a good impression, so you’d better don’t do it, or do it only in the metatags.
15. Keyword dilution
When you are optimizing for an excessive amount of keywords, especially unrelated ones, this will affect the performance of all your keywords and even the major ones will be lost (diluted) in the text.
16. Keyword stuffing
Any artificially inflated keyword density (10% and over) is keyword stuffing and you risk getting banned from search engines.