Most propositional knowledge (knowledge of facts) is pretty easy to come by (at least in principle). There is only one capital of Venezuela, and if you wish to learn the capital of Venezuela, Wikipedia will cooperatively inform you that it is Caracas. For propositional knowledge that Wikipedia knoweth not, there is the scientific method. Procedural knowledge - the knowledge of how to do something - is a different animal entirely. This is true not only with regard to the question of whether Wikipedia will be helpful, but also in the brain architecture at work: anterograde amnesiacs can often pick up new procedural skills while remaining unable to learn new propositional information
One complication in learning new procedures is that there are usually dozens, if not hundreds, of ways to do something. Little details - the sorts of things that sink into the subconscious with practice but are crucial to know for a beginner - are frequently omitted in casual descriptions. Often, it can be very difficult to break into a new procedurally-oriented field of knowledge because so much background information is required. While there may be acknowledged masters of the procedure, it is rarely the case that their methods are ideal for every situation and potential user, because the success of a procedure depends on a vast array of circumstantial factors.
I propose below a general strategy for acquiring new procedural knowledge. First, saturate by getting a diverse set of instructions from different sources. Then, distill by identifying what all or most of them have in common. Finally, improvise within the remaining search space to find something that works reliably for you and your circumstances.
You can't turn every casual coffee drinker into a World Barista Champion in three hours. And even a barista champion will lack knowledge about, say, the breakdown of organic acids over time. When I teach, my goal is to saturate people with general coffee knowledge, and then quickly narrow in on their specific circumstances.
A purely procedural class will give someone a very flimsy, robotic knowledge of one way to make coffee. A purely theoretical class will be interesting, but leave people at sea when they want to make a good cup. Start with theory, move on to procedures. And all times be fueling the session with cups of great coffee!