Water, water, water - I can not say enough about water. I brewed a lot of beer in my college days when I was in Sweden. The water there was pristine and clean - not overly treated with chlorine or other chemicals. I took the same recipe that I tuned to some success overseas back to my house in Northern Virginia and it was so bad that I poured it down the drain. The only difference was the water.
Distilled, filtered, bottled or whatever - make sure your water is as pure as you can get it.
Next is the sterile environment mentioned above. The whole fermentation process is a controlled "rotting". Any uninteded bacteria or germ will grow like mad in the wort and produce a taste or aroma that may not be intended.
I started using Cooper's Beer kits. I followed the instructions but added 5pounds of sugar to the mix. This was the college boy in me trying to up the alcohol content. It worked - made strong beer - but the taste was not a good as it could have been. Once I got better and started to brew for quality rather than qauntity, the beer kits provided a very good and forgiving recipe.
Once I went further, I would add extra ingredients to a beer kit (some finishing hops or an extra type of malt). Then I went to the full 'scratch recipe'.
It is a lot of fun and is a hobby that garuntees you friends (at least at college it did).
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