Proportion really matters, and harmony with the buildings in and surroundings of the garden. In a well designed garden you are aware of this harmony though you may know nothing about how it was achieved.
If you'd like to know more about how it can be achieved I'd recommend John Brookes' Garden Design Book. In the chapter Learning To Design, Choosing and Using a Grid, Brookes shows an excellent way to create this harmony, which is always the starting point for me in any design.
I'm interested always in the underlying design or philosophy behind ideas of all kinds, not just gardening ideas, and in looking at things from different perspectives.
For a completely different perspective on your life do try to see Around The World in 60 Minutes on BBC 4 - it is on BBC i player for another four days. Brilliant.