Following yesterday's post on design principles for fictitious corporate websites, I thought I'd cover a related category -- common rookie mistakes designers make on the technical side. Here are a few things you absolutely don't want to do, or you will totally regret it:
Announcing or linking a domain name before you've registered it. As with the delightful saga of Rowan and Big & Awesome, if you publicly mention a domain name and haven't registered it, be prepared for somebody else to register it for you. Maybe even somebody who doesn't have your best interests at heart.
Putting content up on a server before you're ready for it to be seen. If you have photos up named girl1 and girl2, somebody is going to look to see if there is a girl3. If that girl3 photo is on the server but nobody was supposed to see it for another four weeks yet... well, you've put yourself in a fine pickle, haven't you?
In general, it's wise to lock down a server so that prowling eyes don't see anything you'd prefer to stay hidden. Along those lines, don't allow your web server's file structure to be browsable, and don't use a predictable (ex. sequential, numeric, as above) naming scheme.
You also won't want to put anything you don't want players to look at in a robots.txt file. Players aren't robots, and will be curious to see what it is you don't want robots to look at. Just keep it offline until it's time.
Putting up a solvable puzzle without its reward content live yet. This one is problematic on several levels. The common example is the username/password combination that only starts working after it's been up for several hours/days/weeks. The problem is that your audience may have tried the correct combination and concluded, upon it not working, that it wasn't correct -- and never trying the right thing again. Frustration city.
For other kinds of puzzles -- leading to new URLs, for example, or to other specific pieces of content that simply aren't up yet -- if the reward isn't there, the players will either erroneously assume they're wrong and will keep working, or will feel cheated that they jumped through your hoop and didn't get a treat out of it. Neither one is good news for your project. You can't let player work go unrewarded and expect to maintain an enthusiastic audience.
You may think you have a few hours or days of grace time, and that there is absolutely no way anyone would get there before you've put the reward or linked content up yet. You're almost certainly wrong. But either way, do you really want to bet your whole project on it?
Using sloppy source code. This category includes storyworld-breaking foldering schemes (ex. /dev/clients/burgerking/approved). It might include commented-out links to sites you don't want discovered yet, or notes to other developers on the team (or to yourself). In the ARG world in particular, looking at source code is a common activity. You'll want yours to be as smooth and clean as a bar of soap. Don't leave anything your players might grab onto... unless it's on purpose.
Domain name contact information is a gray area. For some games this information is in bounds, for others it's clearly not. Players tend to be respectful, provided you're very clearly signaling which kind of experience it is you're running.
If your domain registration is in the name of a character, then the emails and phone numbers in the whois had better be functional. But don't worry to much about domain registrations in the name of your production company. If I were to register an in-game domain as belonging to, say, Deus Ex Machinatio Productions, it's a good bet the audience would recognize that it's not inside the golden circle and simply leave it alone.
The kinds of audiences who would be inclined to look at that information in the first place tend to be sophisticated about picking up on such cues. If you're worried, use a private domain registration service.
This is just a roundup of the few rookie tech mistakes on the top of my head. I'm sure some of you have some glorious, glorious war stories regarding more. C'mon, share them so we may all learn from your example. There's no shame in doing it wrong from time to time!