To achieve the best WordPress SEO results possible there are a large number of factors that you might consider. However, looking at lists of these factors can disguise their relative importance. Whilst there are many things you can do to fine tune your SEO, here I am just looking at two key aspects that you MUST get right if you are to achieve best WordPress SEO (or indeed good SEO for any site).
The biggest mistake you can make with SEO is to pick the wrong keywords. If you pick highly competitive keywords which are dominated by large companies with aged domains, high page rank and lots of backlinks (and marketing departments making sure it says that way) you have no chance of a high ranking, however much time and effort you spend on SEO.
If you are serious about having best WordPress SEO you must spend time on keyword research before you set-up your site and find keywords that are not overly competitive but have a reasonable search volume. Search for these keywords and look at the sites that come up, if you see sites like article directories on the first page that is a good sign.
Research suggests that if you are in positions 4-9 on page one of the Google search results you will get about 2% of the traffic (so if there are 1500 searches per month for your keyword you will only get one visitor a day). Therefore you really need to find keywords where you can get into the top three.
Once you have found your keywords, for best WordPress SEO purposes, it is advantageous to include a primary keyword in your domain name.
Search Engine Optimized Content
For best WordPress SEO the pages and posts on your site must be properly optimized for the keywords you have selected. This means that they must be written in a way that makes the search engines understand that they are highly relevant to these terms.
This is achieved by use of the keyword in the title, headings, in the text (properly positioned), in the graphics ALT text and in link anchor text. The keyword can also be empathized by, for example, making it bold. The search engines also look at the context of the keywords so it is a good idea to include other keywords in your niche in the text (even if you are not targeting them).
At the same time as thinking about the above best WordPress SEO also requires that the content reads well for your visitors and is valuable to them.
A WordPress plugin that helps in this respect is SEOPressor. Although there are numerous other tools and services for checking SEO I like this because it is integrated into WordPress and runs each time you save or update a page or post.