1. Using the Wrong Equipment
   When you start making your wine, don't just grab anything you see to make your wine. Some items like wooden spoons cannot be sanitized easily and might taint your wine. Proper winemaking equipment is made of food-grade plastic, glass, oak or stainless steel and is designed to give you the best results possible.
2. Dirty Equipment
   Cleaning means removing ALL visible residues. This step is really important. It's kind of like washing your dishes—you aren't likely to make dinner with dirty pots and pans. Always use an unscented detergent on your equipment and rinse well. Once everything is clean, you can start sanitizing.
3. Poor Sanitization
   Sanitizing means treating equipment with a substance that will reduce or remove bacteria. There are several sanitizers you can use, including metabisulphite solution and Iodophor. They all work a little differently. Clean and sanitize everything that touches your wine—fermenters, carboys, hoses, thermometers and spoons. It's easy and worth it: ninety percent of winemaking failures can be traced to poor cleaning or faulty sanitation.
4. Ignoring or Changing the Instructions
   Follow each manufacturer's instructions carefully. Wine kit manufacturers usually have plenty of experience making wine, and their instructions should be clear and easy to follow. These people find the best procedures for getting the best possible results from the ingredients in the kit.
5. Using the Wrong Water
   Many people think they need to be concerned about the water they use in winemaking. In reality, this is one of those 'problems' that is not a big deal. If your tap water is drinkable, chances are you can make wine with it. That said, some water can leave your wine hazy or give it off flavors. If you know your water is very high in minerals, is metallic, or has high levels of chlorine, you should think about getting a water filter or using bottled water.
6. Not Adding the Yeast Correctly
   Be sure to follow the kit instructions when adding your yeast. We recommend sprinkling the yeast over the surface of 18 to 25°C (65 to 80°F) juice and not stirring. If the temperature is wrong, the yeast won't be happy. And if you stir it in, you can suffocate it.
7. Poor Temperature Control
   Kit instructions tell you to ferment your wine within a specific temperature range. We recommend 18 to 26°C (65 to 80°F). Yeast likes these temperatures and it doesn't like fluctuations. In other words, yeast is going to be happy in the same kind of environment that people find comfortable. Temperature control is important, but you don't need to get obsessive over it. Thousands of people make great wine in a closet in their apartment. Just use your common sense. If you live in Manitoba, don't make wine in your garage in the winter. If you live in Texas, don't make wine in your attic under the sweltering summer sun unless your attic is air-conditioned.
8. Adding Sulphite and Sorbate at the Wrong Time
   If you add these too early, your wine will stop fermenting and the yeast won't convert any more sugar into alcohol. The wine will end up extra sweet and the alcohol level will be low.
9. Leaving out the Sulphite
   Kits include a package of sulphite which you stir into the wine. Sulphite prevents your wine from spoiling, so please don't leave it out. Wine without added sulphite may have a shelf life as short as one month. Some people blame sulphites for headaches, allergic reactions and hangovers. In reality, these conditions are usually caused by compounds other than sulphite. Winemakers have been using sulphite for thousands of years, and modern winemakers (like you) still can't do without it. However, if you think you are sensitive or allergic to sulphites, please consult your doctor.
10. Not Stirring Enough
    Eventually you need to clear your wine. You do this by adding natural substances like gelatin and clay called bentonite. These come with the kit and need to be dispersed thoroughly throughout the wine. This means stirring and stirring and stirring. Stirring also is important to drive off excess Carbon Dioxide.