Here are a few tips from Maria Rodale's Organic Gardening-- excerpted from a Country Living (January 1999 issue) sidebar:
Think long term. It shouldn't be 10 to 20 years, as is common in the US, but a hundred to a thousand years, as in Europe.
Think low maintenance. Edge, mulch, and avoid constant pruning. [And stop pollarding trees that don't need to be pruned into popsicles!]
Think natural. What's the impact on the environment?