Opening the book…
Wood has a direction, and fighting it tears out chips, dulls edges, and ruins surfaces. Grain rising toward your cutter is asking for trouble; grain sloping away planes and routs clean as glass. A minute spent reading which way the fibers run saves you sanding out tearout later, or worse, scrapping a show face. The wood is telling you how it wants to be worked. Learn to listen and the tools do half the thinking for you.
Look at the edge and face to see which way the fibers slope, then plane, joint, or rout downhill, with the grain, not against it. When routing edges, feed so the bit cuts into the grain rather than diving under it. On figured or swirling grain where the direction changes, take lighter passes and keep your tools keen. If a cut starts tearing out partway through, stop right there and try feeding from the other direction instead of forcing it.
Crosscutting and end grain don't follow the uphill-downhill rule the same way; there you manage tearout with a backer board or a scoring cut. And wild, interlocked grain has no good direction, so you fall back on sharp tools, light cuts, and sometimes a scraper or sandpaper instead of a plane.