Learning how to do keyword research starts with brainstorming.  Come up with as many different words/phrases people might use when searching online about your niche topic.  A quality keyword tool will prove invaluable.  
And check out what your competition is using – type your keyword into Google’s search box and study the websites that come up on page one of Google’s results page.  Open each website in turn, go to the View menu, choose Source, and look for the line:
“<meta name="keywords" content=".
Use the Ctrl + F function to help you find it - just type it into the "Find" field and click "Find Next".
Following this will be a list showing you what keywords that website is using:
<meta name="keywords" content="gardening, plants, plant names, garden, herbs, rose, tropical, gardening, vegetable, botanical, landscaping, home improvement,">

Keyword research freebies

Start your own list – use it as a wide base from which to do further in-depth keyword research.  Following are some free online resources to help you develop your list:

• http://www.technobloggie.com/keyword-tool/keyword-report.php
• http://www.nichebotclassic.com
• freekeywords.wordtracker.com
• http://tools.seobook.com/general/keyword/ - this site bases its information on data provided by the Overture keywrod suggestion tool.  If you prefer, you can godirectly to the Overture search term suggestion tool at http://inventory.overture.com/d/searchinventory/suggestion/.
• Other resources include an online thesaurus at http://thesaurus.reference.com/ and the online dictionary at http://dictionary.reference.com/.
• There is also a free online tool available at http://www.apogee-web-consulting.com/tools/keyword_tool.php that enables you to view your competitor's keywords.

With Keyword research analysis you compare the results of the previous chapter (How to do keyword research) side by side to see which keywords have a reasonable number of searches per month whilst at the same time have relatively small competition.  You will also analyze your competitor's websites to see how well search engine optimized they are.
The R/S value shows the number of Google Results divided by the number of Searches.  Here you are looking for a low R/S value.  The lower the R/S value, the less competition you have and the more chance you have in getting your site ranked number one on the Google Results page.  The keyword research analysis below shows there are some as high as 30.68 - you'll want to avoid these.  Better ones for beginners to target are 1.43, 1.45, or 1.58.
These are the keywords you should be considering to base your web page content around.  Later, as you gain more expertise you can try some of the others.

What is PageRank

PageRank is Google’s way of showing a web page’s importance or relevance to a particular keyword.  In Google’s eyes, the number of other websites that link to your web page ADDS to your site’s relevance to a keyword (like a ‘vote’) – the more, the better.
But external links is not the only factor determining Google’s estimation (or PageRank) of your site.  It also matters how important the other websites (ie your ‘voters’) are.  The higher their own individual PageRanks, the greater weight Google places on their links to your site.  In other words, if “important” people link to you, then their links count for more.
Your own links between the internal pages of your own website also add to your PageRank.  The more pages with keywords in their text which act as links to your other pages, the better.  These are called anchor texts and they confirm to Google that the pages are indeed relevant for the keywords being used.
PageRank is a measurement - a numerical weight assigned to a website and the maximum is 10/10.