Many SEOs use a check list when they need to redesign a web site. That helps tremendously, but some aspects of SEO and site redesign defy such a mechanical approach, especially when you’re working with a client. Sometimes it helps to step back and consider the whole picture, as an artist would step back to look at a painting.
Your first step should be considering what you already have to work with. Try to go through the site with fresh eyes. If the site was designed a few years ago, it may have been state of the art at the time, but now looks like it's fallen behind the times. In truth, it has; visitors may be looking for something more exciting (or at least more interesting) and Google surely wants to see something other than what it saw five years ago!
Don't look upon a site's age as all bad, however. Sure, a site that hasn't been redesigned in a long time looks old, but it has something a newer site doesn't: trust. Google and the other search engines look at a site that's been around for several years in the same way that a bank looks at a customer with a very good credit history built up over time. When you combine that status with a great site redesign, you can achieve excellent results.
If you're the SEO in charge of redesigning your client's web site, you'll want to ask lots of questions. Your client may not be able to answer them all off the top of his head. Still, if you want to do a good job, it's helpful to know as much about the site and your client's industry as you can. How competitive is the industry? Who are your client's main rivals? When was the site last redesigned, and by whom? What was done? Do you have a history of the site's traffic and conversions for at least the last several months? Think of those questions as just your starting point.
You can expect to do a certain amount of education as to the nature of SEO and the kinds of results that can be achieved. You may find yourself gritting your teeth if you encounter one of those clients who expect to reach the top of the SERPs tomorrow. Be polite and courteous; you and your client will see a better site emerge from this job if you're working as allies than if you're butting heads. Try to have a clear goal in mind before you start changing the site, whether it's number of visitors, conversions, position in the SERPs, or what have you. With a project like this, you need to have something to work towards, else how will you know when your work is complete? (Granted, the job of an SEO is never really complete, since SERPs are dynamic, but you get my point).
Search Optimization 
