Turn off equipment when it's not being used. This can reduce the energy used by 25%; turning off the computers at the end of the day can save an additional 50%.
Encourage communications by email, and read email messages onscreen to determine whether it's necessary to print them. If its not don't!
Reduce fax-free related paper waste by using a fax-modem and by using a fax cover sheet only when necessary. Fax-modems allow documents to be sent directly from a computer, without requiring a printed hard copy.
Produce double sided documents whenever possible
Do not leave taps dripping always close them tightly after use. (One drop wasted per second wastes 10,000 litres per year)
Install displacement toilet dams in toilet reservoirs. Placing one or two plastic containers filled with stones (not bricks) in the toilets reservoir will displace about 4 litres of water per flush - a huge reduction of water use over the course of a year.
Find a supply of paper with maximum available recycled content.
Choose suppliers who take back packaging for reuse - eg Dick Smith take you empty ink cartridges for recycling
Instigate an ongoing search for "greener" products and services in the local community. The further your supplies or service providers have to travel, the more energy will be used to get them to you.
Before deciding whether you need to purchase new office furniture, see if your existing office furniture can be refurbished. It's less expensive than buying new and better for the environment.