This is a question that I get fairly often. It is also one I go over in detail when we are in the process of designing a site for a client. The simple answer is as often as you can. The realistic answer is a blog, or a resource section, testimonials, quarterly. The reality is 90% of the time the client does exactly what we advise is the worst thing you can do- nothing.
Let’s back up a bit. When we design and build a site for a client we go into great detail about how websites are ranked by the search engines such as Google, Yahoo!, Bing, MSN, etc. We explain the difference between organic results and paid results, we explain about spiders and bots….Uh-oh, have I lost some of you? I’ll back up a bit more. Search engines like those just listed send out what is called spiders and bots to comb the internet for information that is then used to sort and rank websites so that when an inquiry comes in from a user the search engine is able to respond with the appropriate websites. These spiders and bots will continue to return to your site and continue to update the 
information it has on your website IF you continue to feed them NEW information i.e.; fresh content. If, however, you do not continue to feed them fresh content they will eventually stop coming by your website because they will have recognized that there is nothing new there and nothing new to categorize and sort. To sum up, If you continue to feed the spiders and bots fresh content then they will continually be sorting and ranking your site and you will organically rise in the search engine results. If you do not feed the spiders and bots they stop coming and your website will drop in the search engine results. What I have just describe is all ORGANIC SEO (Search Engine Optimization). And if you are writing and posting your own blogs or resource material, it will cost you nothing.
Paid SEO is when you pay for ads to appear when certain keywords are typed into the search window in certain geographic areas, and then a user clicks on that ad taking them to your website. This is often referred to as Pay-Per-Click. This, too will help your website to raise in search engines rankings…but only until your pay-per-click campaign is running. Once it is over, you will be right back where you were before, with no fresh content. The other problem with the pay-per-click ads is that someone can click on the ad, stay on your site for 2 seconds realize it is not want
they want and leave, but you still have to pay for that click. Competitor will often click on each other’s ads to run the money out and remove the ad from appearing in the results, and you guessed it, you are paying for all of those clicks as well. You may get some good action from the ads, or you may not, it depends on if you have selected the right keywords to focus on, and each word or phrase has a different price per click. So the absolute ideal phrase for you in your area may cost $9 a click while a so-so phrase may cost $1 or less, and once your allotted money has run out your ad is removed and the next ad appears. For some businesses this is a solid piece of a marketing plan, for others not so much. There is of course more to it than I have laid out here, more nuances, but for the sake of this blog, it should give you a good enough idea to follow my thoughts.
So to get us up to speed: Organic SEO- fresh content provided on a regular basis providing ongoing information to the search engines organically increases rankings and sustains them for a longer period of time.
Paid SEO- artificial bumps in your traffic based on pay-per-click and paid ad placements temporarily boosts your rankings and they will fall back down once the campaign is over without fresh content.
Original Question: How often should I be updating my website? As often as possible to keep those spiders and bots fat and happy with information about your site so that you can organically rise in the rankings. Bar none, the best way to do that is through a blog. By blogging twice a week I add on average 1700 words of fresh content to my website every week (I am already nearly 800 words now). That does not include all of your wonderful comments, which probably pushes it to over 2000 + words of fresh content every week or if you prefer somewhere between 12 -14 thousand words a month added to my website. Nice Fat Spiders and Bots.
But you should also be updating your page content on a regular basis. You cannot rely strictly on your blog to do all the heavy lifting. You should be updating projects, new employees, new service or product offerings, you can add a News page and update that with news of your company in terms of achievements, growth, celebrations, innovations, promotions, etc. The Resource section can include a recommended reading page were you list books and/or articles and why you are recommending them. There are plenty of clever ways to provide fresh content to your site to our little visitors happy, and we would be more than happy to discuss them all with you if you are interested in learning more.
Short Answer: As often as you can!
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