Avoid bottles with wine residue around the cork foil (possible heat damage)
Check that the bottle is filled to within an inch of the cork
Don't confuse grape varietals with brands (Riesling "rees-ling" is a grape not a vineyard)
Don't necessary stick to advertised brand names...the smaller wineries have good wines, too and often at a better price (you're not paying for national advertising)
Ask the clerk about vintages or vineyards you are uncertain about
When storing wines:
Store bottles on their sides, to keep the corks moist.
Store wine in a cool dark place, with a consistent year-round temperature.
You can keep unfinished open bottles of wine in your fridge for up to a week. Simply re-insert the cork upside down for a snug fit. Opened bottles of wine will last longer if the air is pumped out (you can buy inexpensive suction devices in wine stores).
When serving wines:
You can bring a refrigerated red to drinking temperature by letting the bottle stand out for 30 minutes. You can also microwave a single glass for just 10 seconds
If the wine is bad because of a dry cork, return it to the wine store