The best advice is the most obvious. If you want to be in shape, you must diet and exercise. If you want to be a writer, you must read and write a lot. These morsels of wisdom should be obvious. The salt and pepper of any prospective pantry. And yet, the omission of the most obvious necessities in any endeavor tend to be the driver behind most failure.
When we are asked for advice on how to build muscle, we tend to avoid these inescapable facts of life, and skip to our more revelatory secrets. We tell people to drink protein powder, how to vary their exercises, when to increase resistance, which exercises target which muscles, etc. We do this because it's the information for which we see the most benefits in our own progress. We don't even consider the idea of skipping out on exercising in general. That part seems obvious, and yet, lack of adherence to the basics is the root of most failure. How many people try to get in shape with whatever new fat cure is yet to be disproved, only to fail to lose any weight because they treated what is at best a supplement as a substitute for dieting.