if you must, try and re-use something from somewhere else before buying/building new
if you must buy new, try and buy/build something with recycled components, which can be reused many times, and then recycled when you have finished with it
household waste
don't make it - seek out products with minimal packaging, reusable or resealable components, and extra-strength or long-life attributes
use as little as possible of the item each time you use it
try and re-use the waste components for something else, instead of binning them
try and recycle as much as possible (usually it's mainly just plastics that are left)
plastic bags
don't get them - actively refuse them - try and carry the items instead - use pockets, both hands, top of head - or a bag you carried with you ready for this moment
re-use all the bags you have already - recycle any large collections you have
do not throw them in the bin
office waste
These tips courtesy http://www.cityoflondon.gov.uk/recycling/
avoid unnecessary printing - if you must, print on both sides of the paper
collect and recycle print cartridges, toners, batteries, phones and other electronics
recycle all paper, cans, glass etc
avoid disposable items such as plastic cups and cutlery - use real ones
source supplies with minimal packaging, made from renewable resources
distribute and file documents electronically
pollution
avoid creating non-biodegradable waste - try to use products and services whose waste components are environmentally friendly
if you possess non-biodegradable waste, pay attention to disposal instructions and legislation, particularly with reference to oil, chemicals, whitegoods, batteries and other electronic devices
try and auction your unwanted goods and devices on ebay etc
try and give your unwanted goods and devices to friends, colleagues and associates
seek out recyclers - they may buy your waste from you, or at least collect it for free