WordPress SEO is basically straightforward if you follow some simple rules:
1. Domain Name and Hosting
Register a domain name including your primary keyword. Alternatively you can purchase an existing domain name. There are WordPress SEO advantages to this so if you can find a suitable name at a good price it is a worthwhile step.
Get a hosting plan where there is an uptime guarantee and pages load fast. If your site gets busy use a plugin to cache the pages/posts. Slow loading will be penalised.
2. Use a theme designed for WordPress SEO
Many themes are designed with appearance in mind rather than SEO. Make sure you use a SEO friendly theme.
3. Configure Wordpress for SEO purposes
Firstly set the Permalinks to "postname" so that the title appears in the URL. Then install one of the many WordPress SEO plugins ("All In One SEO Pack" is the most popular). Configure this to noindex duplicate content, set the titles to what is best for you and enter meta data (the description being the most important).
Use a plugin to generate a sitemap for the search engines.
4. Good Content
Adding good unique content on a regular basis is a key part of WordPress SEO. Search engines like to see active sites so new content as well as some editing of old content is good.
In general big sites are better than small sites for Wordpress SEO purposes so plan to keep adding content on an ongoing basis.
It is best if the topic of the site is focused as the pages will help each other get ranked.
5. On Page Optimisation
For each page/post the keyword should be in the URL, title, headings and at a reasonable density through the text. In particular it should be used in the first sentence.
There should always be an image and the keyword should be in the ALT field.
You should have internal links with keyword anchor text such that all your pages/posts are linked together. Outbound links are good for WordPress SEO when they are to relevant sites but don't have too many and never link to any site which engages in questionable SEO practices - it will reflect on your site.
Make sure that you do not have any broken links.
6. Off Page Optimisation
This is the biggest task which will be on-going.
Your aim is to get as many backlinks as possible. However all backlinks are not equal, the best being from high authority sites using your keyword as anchor text. Links from sites on a similar topic are good as are links from.gov and.edu sites.
One way to minimise the work involved in WordPress SEO is to get on page SEO right (i.e. it is clear to the search engines what your page is about) because a link to a well optimised page is worth more than a link to a poorly optimised page.