I had to do an SEO report in my job a few weeks ago, I found the best thing to do is create a list of every single element of a website, from its usability to its domain expiration. I used 2 websites to find everything: http://www.bukisa.com/articles/315980_how-to-write-your-own-seo-report http://www.seotoolpack.com/seo-tools/ Hope this helps! Good luck!!
Use Google Analytics, Just sign up there and they will generate a code then you will just paste it to your Header.php. The Google Analytics will automatically analyze your website.
Check the title tags, meta tags, h1 tag, anchor tag, keyword density, page load speed, sitemap, robots.txt.