I had the opportunity to take a Viking cooking class a few years ago, and it was fantastic. I learned all kinds of tips and tricks that I continue to use daily.
Probably the biggest lesson I took away was the concept of mise en place, which means "everything in place." This means that before you begin to cook or assemble a recipe, you've checked to make sure you have all the ingredients and necessary tools, and you've also cut, peeled, diced, and measured all the ingredients. Think: lots of little bowls. I used to (and still sometimes do) cook via the "find it as you need it" method. Needless to say, this wastes time and resources - especially if you get all the way through a recipe before you realize you're missing a key ingredient.
As I've begun to experiment with baking, I'm learning how important this is. It makes things go so much more smoothly to have everything out and ready to go.