Web development must start from a clear understanding of the environment and goals within which the site will be judged/used/seen.
Is the site primarily promotional? Informational? Is it to sell? Internal communications? Will visitors find it on their own, or be led there from an established community?
Most sites live and breathe information. Information is what attracts visitors. Information is what search engines index. Information is even what brings internal employees to fire up their browser and look at "the intranet".
Very often, a significant investment in information—content—is necessary to make a site succeed. For most sites, it's the bait on the hook.
Good "information architecture" is key to getting value from the information. It has to be findable by the users. It has to work "naturally" or "intuitively"—something that only happens with superior architecture and design.
Site navigation largely comes out of information architecture—how will the users wish to travel through the information?
Design is how your site looks. And how that look relates to your storefront, stationery, packaging, billboards, and television ads. Or any other aspect of your business identity.
Implementation includes page coding, back-end server programming, database design, implementation of other packages. Implementation should best be conservative. One user who finds your site doesn't work tells 10 friends; or, worse, posts about it on a large mailing list. One user trying to show it to a friend—and failing— is a black mark against your business.
Maintenance is key to an ongoing successful site. A successful site is dynamic, ever-growing, current. The deadliest thing you can present to the world is stale information.
How all these updates are performed makes a cost and time difference to the people who perform them, and will end up making a big difference to how often the site is really updated.
Monitoring the behavior of your site is important. Complaints from users shouldn't be the first way you find out about problems! Many kinds of problems can be discerned from the site access and error logs, which should be reviewed frequently.
Hosting and other service providers make key contributions to the success of a site—and sometimes even bigger ones to its failure!
Lots of money can be saved by using shared hosting, and with a good provider this is a very viable choice for most commercial sites. These plans usually include in their low fees critical and expensive maintenance activities that can greatly increase the real cost of dedicated hosting.
Browsers remain a rapidly-changing class of software. In general, care should be taken to avoid locking people out based on the browser they use. A disgruntled user generally tells ten or more people of his unhappiness!