Start with the top, bottom and side navigation schemes, and follow up to make sure that info flows from page to page (and link to link) in a logical fashion. Content comes
next. Do you have enough?
Check the overall design, and then work on a page-by-page basis. The home page is prime territory, followed by the about us, contact and shopping pages. If
it's an e-commerce site, assess the shopping cart's functionality as well.
After the quickie review, you can focus on each area that needs improvement, and then work on the more search-specific tasks.