1. Never set up a client's computer without getting them to decide where they want everything. No matter how logical you think a setup is, the client will invariably want it arranged a completely different way.
2. Always carry a keyboard, hard drive, or pci device with you when you walk around the building. It's a simple way to communicate the message, "I'm very busy working with things you don't understand, no matter how many computer game boxes you may occasionally see on my desk."
3. Always face your monitors away from the door, so no one see you slacking off with a computer game.*
4. Never let you office get completely cleared of spare equipment. Once it's empty, people will begin dropping off their old stuff and your office will fill right back up. Spread things out so that there's just enough space to move around, and no one can use you as a junkyard.
5. Always have ear buds and something to listen to. You're going to spend a certain amount of time in people's offices, and if you have to listen to them chatting up co-workers about how they don't like Mondays, they wish it was the weekend, and what they may or may not do for dinner, you will go crazy.
6. Always write your blog posts on company time.
*Not that I've ever done this. Ever.