I made buttermilk pancakes last week and used half a cup of buttermilk powder for the dry mix instead of measuring fresh milk, @parker183, and they came out way too thick and dry. Now I always pour the liquid first, then add the powder or vinegar slowly while stirring. I also started writing the recipe steps on a little whiteboard I keep on the counter so I don't skip around. It helps me catch stuff like that before I ruin another batch.
All that planning and writing stuff down just kills the fun of cooking though. Half the time my best meals come from throwing things together without measuring anything.