What is important to choose a wine is to know that more expensive is not always better and the price of each bottle refers to the winemaking process and is not an indicator of quality. The most relevant factors in the cost of a bottle are:

• The better or worse care of the grapes in the vineyard

• whether it has been aged in the bottle or not.

• How long the wine was stored in the warehouse.

• The price of inputs used, labels, corks, technology, bottle, etc…

Ultimately, a young wine is different, not worse, than a reserve wine.

As for the aroma and taste of wine concerns, there are no recipes, and sensory experience of wine tasting is very subjective. However, we can say that white wine should have a strong acidity that waters down your mouth at least 3 times after taking the first sip, as well as the fruity and fresh print on the palate. In the case of red wines, high acidity is not sought, unless the wine comes from Italy, whose wines are recognized just by having this attribute. These bottles also should have a completely drying astringency mouth, this may indicate, if reserve or guard, that is not yet ready for drinking, because this feature is softened by years of bottle aging. In either case, wines should not be moldy or musty smelling, even less if they were created to be consumed young.
If we are facing a great wine, we find that the glass reflects at least one aspect of each stage of processing, an herbaceous note of the vineyard, a fruit of the grape aroma, a floral from fermentation, and the aroma characteristic of vanilla and wood snuff. However, beyond the recipes, your goal should always be to excite those who test it, so I cannot resist returning to it in the future.
Another doubt is the temperature that each wine should be served, and although it is a matter of taste, the experts recommend cooling white light wines as Sauvignon Blanc and Pinot Grigio at 10 ° C, while denser whites aged in wood such as Chardonnay or Viognier, should be 12 º C. Sparkling and sweet wines are consumed both at a temperature between 6 º C and 8 º C. Lighter and younger reds are served about 12 º C. Finally, dense reds reserve or guard should be opened when they are between 17 º C and 18 º C, although it is common to hear that they should be taken at room temperature.

***Grabbed from: http://blog.uvinum.co.uk/choosing-good-wine-955340