1. You don’t taste as you go.
2. You don’t read the entire recipe before you start cooking.
3. You make unwise substitutions in baking.
4. You boil when you should simmer.
There are 41 mistakes in all, and many of them are very specific. Each has advice for the right way to do it. Link -via Metafilter
(Image from: Mefite inigo2, who said his biggest mistake was to leave his cockatiel near the chocolate fountain. He also updated by telling where he got the images.)