A 75cl bottle of wine is enough for 6 glasses.

If you serve your wine from the bottle, opening it an hour beforehand will not make any difference to its qualities unless you pour out a small amount so as to increase the surface area in contact with the air.
This will also enable you to taste it and find out whether it needs to be decanted. It is advisable to smell your glass before you use it to make sure it has not absorbed any foreign odours (washing up liquid, cardboard, etc.)

To begin with, pour a drop of wine into your own glass and taste it before serving your guests.
For wine tasting sessions only fill each glass to one third of its volume.
When dining, it is recommended that you half-fill each glass.

You may have the best intentions at heart in wanting to fill your guests’ glasses completely, but in fact this prevents the glass from fulfilling its purpose of channelling aromas. If it is only one-third or half-filled, the glass can then trap the sometimesfleeting scents hovering at the surface of the wine in its empty upper half. Always stand to the right of the guest you are serving and hold the bottle by its body, without letting it touch the edge of the glass.

Drink in moderation and remember to serve your guests water at regular intervals as well…