The important part of SEO is keyword.The keyword research should be thus done before creating and collecting content for website.For the purpose you can use the keyword research tools.Doing the research on the keywords using the keyword research tools two things shoule be kept in consideration.
1.The number of time the keyword is searched.
2.The number of website competiting for the same keywords.
Use keywords that has maximum number of search.Donot use the the words as the keyword if the competition for that word is very fierce although the number of search is maximum.Use the keywords that has more number of search in search engine and less competition.If the competition for the keyword is less you can easily ranked above in search engine. Thuus the competition should be less to get more number of traffic.The high competitive keywords will not help you get above in saerch engine.
Also give the keywords attractive looks by making it bold or underline it.This has direct influence on tne traffic. The top keyword can directly drive traffic towards your site. It will directly help on getting higher page rank.Analysing the top ranked website can also help for ranking well.Also link your website to the properly ranked website for getting the bettet pagerank. If you get the backlink from the website having pagerank 5 then u are sure to get the rank of 1 or 2.
Also the density of keyword should be considered.Use keyword frequently in your content part. If you use 1000 words then use keyword for at most 10 times.Using keyword greater than this is also not proved good because if keyword is excessively used then google may take it as the spam. Use the key words at the very begining and end of content.This will strengthen your page.It is also good if you include your keyword in your page URL. The maximum traffic of the website is the direct effect of the optimization and research of keywords.Keyword resarch and the traffic and direct influence on the page rank of the site.
If the keyword is resarched prooperly and proper keyword is use then it will drive traffic in lagre amount and thus made diret influence on pagerank of the website.