In the old days, it was far simpler to choose wine in a restaurant. The standard rule was red with meat, white with chicken or fish, champagne as an aperitif and brandy or a liqueur after the meal. The men would order the wine and the women (despite having arguably superior palates and being able to remember taste profiles better) would drink whatever the men ordered.
Today there are red wines which suit fish and chicken, white wines which suit meat and game, wines from the new world as well as the old world, and wine lists several inches thick. Unless you are a wine connoisseur, there will be pages and pages of wines you have never heard of.
No wonder choosing a good wine is so stressful, especially when you are choosing for a whole tableful of people. Making a poor choice will not ruin the meal but it can be embarrassing, and it is worth learning a few tips about how to order a suitable wine and how to get your money's worth.
Remember that restaurants make more profit on wine than they do on food, especially on cheaper wines. A cheap wine might have a 100% or even 200% markup, whereas an expensive wine will have a much smaller one. A restaurant might pay $5 for a bottle and list it for $15. The same restaurant might pay $40 for a bottle and list it for $60, so you can see that a more expensive one might work out as a better deal, as you are not paying three times what the wine is worth.
Not many restaurants age their own wines. Instead they trust their wine merchants who in turn rely on good sales. This is why a lot of wines on a typical restaurant menu will be very young. New world wines (and some old world wines) have been made to mature early for several decades and it is these which make up most of a typical restaurant wine list.
Bear in mind that it is very difficult to find a perfect food and wine pairing (even if everyone at the table is ordering the same dish) and lower end restaurants might not have a sommelier (wine waiter) to assist you with your choice. You might want to play it safe and choose something you are familiar with, or you might like to choose something that looks interesting but is unknown to you.
If there is a sommelier however, he or she is there to help people choose the right wine, so by all means ask for their input. It is the sommelier's job, after all, and asking for a suggestion is a good idea, not a copout. You can give the sommelier something to go on, perhaps with, "I fancy something from the New World" or "perhaps you can recommend a dry white." You should also indicate your budget. You can do this by pointing at some figures in the price column if you do not wish to state your preferred price in front of the others at the table.
A good sommelier will be able to match your budget to something which will complement the food. You do not have to accept the advice of the sommelier if you do not like his or her suggestion, but if the wine does turn out to be a good one, remember to note the name, producer, vintage, and country of origin so you can impress future dinner guests.