1. Check Broken Link 2. Check Error in Coding of each page through w3c validator 3. Check Domain Age 4. Dmoz and yahoo listing 5. Check current keyword position in Major search engine 6. Check Keyword density 7. Content of the website it shoud be informative and descriptive, rich, unique, fresh. 8. Check H1 tag, header, footer 9 Images, If images is too big and large break that image into 2 to 3 parts. 10 Website opening speed in browser 11. website size 12 check Alexa Rank 13 Check Keyword Competition 14. check website grade through website grader tool 15. Check title, meta description, meta keywords of website 16. Check http status of website 17. check any canonical issue in website 18 check dynamic pages 19. check doctype declaration in Coding 20. check website for flash, frame script, iframe script
yaa i'm agree with cellhub and also check client business area, website pages, product popularity, compare your details with competitor, website layout
All these factors are really helpful for the optimization of the websites because these factors some time as well to capture the marketplace for most of the keywords over the main search engines. Google,yahoo & msn.com
All the mentioned steps are useful..it is better to create an checklist (better in an Exel file) and follow these things on all your SEO assignments...