The biggest mistake you can make in setting up a new Web site is to figure that you are done when the site goes on-line. You need to treat your Web site as a living document or it will become a dead one. If you don't believe me, think about how many times you return to a site that you know hasn't changed in a long time. Once you've seen what it has to offer, what is the point of going back?
For your site to be successful, you must continually find ways to make it more interesting. In other words, to keep your Web site alive, you have to keep feeding it. This is a serious commitment that should become a regular part of your marketing strategy. Remember when your mom wouldn't let you have that dog unless you promised to feed it and take care of it? Well, don't ask for a Web site if you don't plan to maintain it.
When you devise your site plan, you should include ideas for how you can integrate site innovation into your current marketing procedures. For example, every time you send out a press release, your standard procedure should include a step that puts the release on the Web site. All new marketing literature should be converted to a Web-friendly format and put on your site. Your support staff should keep track of frequently asked questions, and you should make sure those questions and their answers are placed on your site somewhere. The more you integrate Web site considerations into your standard business procedures, the easier it is to keep your site up-to-date.
If you can't update the site yourself, find someone who can. That means training your own personnel with the skills necessary to work on the site, or retaining a consultant who can take care of it for you. You'll probably get a better deal if you purchase a long-term support contract rather than paying for updates piecemeal. Having that contract also encourages you to put it to work: you are more likely to make updates if you are going to have to pay for them anyway.
Plan for later innovation as well. As your site grows, it will probably start to become unwieldy, depending upon how well you organized it in the first place. Expect to reorganize your site once in a while to better accommodate the information you've added.
You may need to plan for changes to your design as well. The more trendy the design, the more dated it will look over time. Imagine two photographs. One is of a man in jeans and a T-shirt. The other is of a man in bell-bottoms and a multi-colored shirt. In the first one, the clothes are serviceable, but could belong to any era. So, you tend to focus on the man, not the clothes. In the second, the clothes are dated. You tend to focus on the clothes, but your reaction is one of amusement, perhaps with a hint of derision. You obviously want to avoid getting a similar reaction to your site.
I'm not saying you shouldn't use any trendy design elements: just be prepared to change them as the trend changes. If you stick with traditional design in the first place, you can ease your site maintenance burden. There is an industry saying that good design is design you don't notice. As I'm sure you've noticed, many Web designers thumb their nose at that premise.
Site visitors love getting something for free, so you should put a virtual candy bowl on your site. I don't literally mean a bowl of candy, of course. What I'm talking about is free access to useful tools or free downloads. Dan at Clearwater Landscapes (www.ClearwaterLandscapes.com) gives his visitors free access to a mulch calculator I wrote for him. You enter the square feet of the area to cover and the thickness of the mulch, and the calculator tells you how many cubic yards of material you need. Visitors love this kind of tool and it gives them a good reason to return to the site.
No site plan is complete without considerations for keeping it healthy after it goes live. To keep it alive, you periodically need to feed it new content, groom the design, and teach it some tricks to amuse your visitors.