You're chasing your tequila. Tequila is actually meant to be sipped, not taken with a shot, and chased with salt and a lime. If you're drinking good-quality tequila, you won't need to chase it with anything at all—it will taste great on its own.
You're drinking your alcohol warm instead of chilling it in a salt and ice bath for 10 minutes. Yes, desperate times and all that, but 10 minutes is not a long time. Fill a bucket with equal parts ice and water, add a handful of coarse salt, and place the bottle in the bucket up, making sure the ice mix goes up to the bottle's neck. The common mistake MacNeil says people make is only having the bottom of the bottle on ice. If you do this for 10 to 20 minutes, your alcohol will be as cold as it would be after two hours in the fridge.
You're filling your wine glass to the brim. I'm not saying that you don't deserve all of the wine, but instead of one glass filled to the top, have two glasses. MacNeil says the less wine in your glass, the more it's able to open up with the air, and it will taste better.
You think you can't open your beer bottle without a bottle opener. You don't need a bottle opener at all, actually. When in need, use a house key!
You're not putting your red wine in the fridge. Karen MacNeil, the author of The Wine Bible,recommends putting red wines like pinot noir or cabernet sauvignon in the refrigerator. The colder you chill wine, the more it will show its freshness, whereas the warmer the wine, the more it will show its alcohol. The rule of thumb is this: Red wines taste best at about the temperature of an air-conditioned movie theater, or about 60 degrees Fahrenheit. Liquor stores are usually fairly warm, so MacNeil recommends putting your red wine in the fridge for five to 10 minutes so it's at a cool room temperature. If your wine has been in the fridge for longer than that, let it sit for about 15 minutes before drinking it.
You're opening your sparkling wine by twisting the cork instead of turning the bottle. The right way to open a bottle of champagne is to first remove the foil from the cork. If there's a cage, leave it on to help with your grip, then place your thumb on the cork. Next, angle the bottle and twist the bottom of the bottle slowly. The cooler the bottle is while you're doing this, the less pressure there will be, which means it won't make a mess.
You're drinking beer from bottles instead of cans when you're outside. Jeff Alworth, the author of The Beer Bible, says that sun and even artificial light will skunk a beer. This means that as soon as your beer is exposed to light, a chemical process converts compounds in the beer into an aroma that smells exactly like skunk. And once a beer is skunked, you can't un-skunk it. Glass = transparent = exposes beer to light = skunk. You might think that a can is inferior to a bottle, but actually, a can is pretty good at protecting beer.
You aren't filtering your cheap vodka in a water filtration device. It seems like a college myth that putting your vodka through your Brita makes it better, but there might actually be some truth to it. MacNeil says that by putting vodka through a filter, it will achieve a sense of neutrality, making it taste smooth. In a test by America's Test Kitchen, filtered vodka showed an improvement in flavor. The rule of thumb is to run it four or five times to get a noticeable difference in taste.