Smelling, or nosing, the wine
The sense of smell and the sense of taste are so closely intertwined that one could not exist without the other. For this reason, your nose can tell you a great deal about a wine before you even taste it.
A properly designed glass can help capture a wine's aromas and funnel them in the right direction. While glasses intended for use with reds tend to have a larger bowl than those made for whites, both types should taper towards the top, 'steering' the bouquet towards your nose rather than allowing it to dissipate from a large surface area. Swirl the wine in the glass so that most of its interior surface is coated in liquid as this helps to release the wine's aroma. Put your nose well into the glass and sniff.
As with the colour of a wine, its perfume will vary according to its age and composition. The region where it was made can also influence its aroma, as can ageing in oak barrels. Think about the smell. Is it powerful and complex or simple and light? Does it linger or is it soon dissipated?
Grape variety has a profound influence on a wine's perfume. The aroma of Sauvignon Blanc, for instance, is classically described as 'cat's pee on a gooseberry bush', Cabernet Sauvignons are often characterised as having a blackcurrant quality and Pinot Noirs have something of the barnyard about them.
As a wine ages, its aroma may change - white wines often become more honeyed over the years, while young whites are often described with reference to fresh flowers, fruit or newly cut grass.
A good sniff will also give you clues about a wine's condition - if it is corked it will smell musty. A whiff of burnt matches is the hallmark of a wine to which sulphur has been added as a preservative (this is quite common in cheap white wines). An oxidised wine will be given away by a rich burnt scent, similar to that of Madeira wine (an additional clue comes with looking at an oxidised wine, which usually appears brownish in colour).
Be as poetic as you want in your evocation of a wine's bouquet and have confidence in your ability to judge its qualities. After all, there is no right or wrong in anyone's description of a wine - it is just a highly personal reaction to the scent released from the glass.