Get Out There and Fail
Fear of failing sometime steers us towards taking unnecessary precautions to better the odds of success. It makes perfect sense, but it's a shame because when things are overdesigned and overbuilt, we often don't have the opportunity to observe the true strengths of the components involved.
Understand the materials, techniques, and tools you use
Forget cosmetic appearance—the real beauty comes from the strength within. Take the wood species ash as an example. The true beauty of ash, despite its strong grain lines, is its strength and flexibility. These physical properties allow components to be shaped more aggressively. Likewise, fine-grained hardwoods allow us to cut finer details, including joinery and carvings. For those reasons, it is important that the maker have a good understanding of the materials when matching them to the design.
As with most things, you can learn from books about the physical properties of materials, and the strengths of different joints. That's an excellent place to start, but a terrible place to finish. Books and pictures don't adequately convey the strength of a certain material or joint. Descriptions such as "good load strength and medium hardness" or "an excellent joint for a drawer" don't tell you how the material or joint will fare in the real world. Videos are slightly better, but are still poor replacements for hands-on experience. The best way to learn is to experiment. Seek failure.
Gather real-world experience
Here's a simple exercise I use to learn the strength of materials: A project always yields some offcuts. Instead of cutting down over-length offcuts to fit in the firewood box, I first try to break them.
For small pieces, I may try to fold them with just my upper-body strength. Larger ones I may try to break over my knee. But for most offcuts, I set one end on the ground and the other on a block of wood, then stomp on it. It is impressive how strong wood is. Quite often, the wood will kink or bend before it fails.
Apply your knowledge to your designs
We can apply our knowledge of materials and joints to the things we build. Remember that in most projects, the piece of wood taking a load—whether it be a tabletop, chair stretcher, or drawer bottom—is wider if not thicker than our sacrificed scrap and hopefully not the subject of somebody stomping on it.
I think that this exercise will build your confidence in material strength, and possibly get you thinking about using materials in more daring ways.