Well said Fut.
I can add to this the fact that a large glas with the right shape will enable you to follow the effects of decanting perfectly. You might just take a glass and enjoy the development over an hour or so. Too often the complexity of aromas are destroyed by decanting.
But then again, I'm a big fan of slow-food & slow drink
Try to detect the balance of fruit against tannins and acidity on your palate. When it comes more forward during some time in the glass you're heading the right direction. On the nose its often just a matter of becoming more pronounced and 'open'.