Steve wrote a fantastic article about the cumulative and ongoing process that SEO is!!! Check it out below (then go to Search Engine Journal and read it all!):
Organic search engine optimization (SEO) is not a one time project, it’s a process. Similar to a garden, you must tend to it. Sometimes you have an existing garden where the weeds have grown over or nothing is growing. Sometimes you just have a section of yard you are going to rope off, till, then plant stuff in. Like a garden, organic SEO takes time and attention. It may be as simple as setting a timer to water or as complex as starting from scratch. Organic SEO is like a garden – if you don’t water it, it dies.
Soil Considerations
What is the history of the things that have been done to your website for SEO purposes?
Do you have pages chock full of links to websites unrelated to your company, where some of the website no longer exist or even some link to an “adult” website? Did someone hide a bunch of keywords the same color as your background at the bottom of the page? Maybe the site you are going to work on has commented out a bunch of keywords in the HTML code? (I know this is 2009, but some company, somewhere, has this on its Web site, right now.)
Sunlight, Rainfall and Other Factors
Traffic Analysis – Are there metrics on the company’s website? What kind of information can you gather from the statistics on what is going on with keywords, referrers, exit pages, entry pages, bounce rate, etc.? What metrics program does your company use?
We always ask our clients to install the website analytics program we use -
Hitslink – simply because it provides the measurements we need for our clients and also allows for consistent report formats for all clients.
What Plants shall we put in our garden?
Keyword Research – Gather the keywords out of the client’s current website metrics and obtain client input on what they think someone might type to search for them.
We usually use a method that I have used for many, many years. We ask the CEO, (get’s them involved at the top), the receptionist, the sales managers, the marketing director, the CFO and the COO (these two help get things done and also make sure you get paid) to provide five to 10 keywords each and not to share them with each other. This becomes statistically significant when you have different people come up with a keyword phrase more than once. Take these and put them into spreadsheets so we know what department wants what traffic and also to refer to later.
This is the primary keyword stage. You can also correlate what keyword terms got the most traffic and the lowest bounce rate to their Web site compared to what the client expects. Now obviously, you must factor in the fact that if the content doesn’t exist on their Web site right now, they won’t be found for it.
What kind of pesticides would be best to use to combat bugs?
That’s correct – SimpleSEM.com has rebranded to SimplePerformanceMarketing.com. We didn’t want to redirect the entire site at once, so we will be slowly migrating the content and posts to the new Blog. 
Very recently, I noticed a the PR of this very site was dropping with little to no reason. We DON’T condone any Black Hat techniques, we use no paid linking to promote the site, and we have a very good domain history. But, still our PR was precipitously dropping with no reason. I started to dig into this last night and found out we had our ht.access file hacked!