If possible, place your desk so it faces the door, with your back to a wall.(If this isn't possible, place a small mirror on the wall above your desk, or on your desk itself, so you can always see at a glance who is walking up behind you.)
Arrange your desk top according to the ba-gua:
From the seated position at your desk, directly in front of you is the Career area. This is a good (and most logical) place for your laptop or other work materials. Clockwise from there: Knowledge - books, your planner, etc; Family & Ancestors - family photos, mementos, symbols; Prosperity & Wealth - healthy, growing plants, the colors red/green/purple; Fame & Aspirations - symbols of your achievements and aspirations, the color red; Relationship & Love - pairs of things, heart shapes, photos of you and your partner; Creativity & Children - good place for a lamp (preferably metal), the tools & fruits of your creative passions, photos of your children; Helpful People & Travel - your address book/rolodex/Blackberry or iPhone, travel photo or framed postcard, small souvenir. The very center of your desk is the Health area - keep it clean and "happy looking." Yellow is the color of health, if you want to add a yellow paperweight or box for paperclips, etc.
Cleanliness/tidiness are the most important principles of feng shui. The items you add to your desk should be attractive to you, and useful - a heart-shaped box in the Relationship area can hold stamps, the Family & Ancestors area can extend to the top of a nearby file cabinet, if you aspire to be a writer, a cup full of red pencils can sit in the Fame and Aspirations area, your Eiffel Tower pencil sharpener can go in the Helpful People and Travel area...it's simple, really, and when you get everything set up, you WILL feel the difference in the energy!!
"And may the odds be EVER in your favor!"
**In my example set, my laptop is in a rolling laptop case, because I travel a lot for my job. The red dog represents my Aspirations, because I work in Animal Welfare, and if I'm ever known for doing anything really well, I want it to be that.**