Feeding
Feeding is the part of backyard chickens that gives the most trouble to newcomers, and also the part that improves the fastest with deliberate attention. A few weeks spent on feeding carefully — rather than rushing to the next thing — usually outperforms months of unfocused practice. The improvement is not glamorous and rarely shows up in a finished result anyone else would notice, but it is what separates a frustrating hobby from a satisfying one.
The rule of thumb: if something feels off and you cannot say why, the answer is almost certainly in feeding. Slow down, observe, and only change one variable at a time. Keep brief notes if you can. After a few sessions you will start spotting patterns that were invisible at the start, and feeding will stop being a problem.
That is the short version. Backyard Chickens rewards patience more than cleverness, and almost all of the visible improvement in the first year comes from showing up regularly rather than from any single decision about gear, method, or feeding. Most of what is on this site assumes the same thing: that you intend to keep at it, and that you would rather be quietly competent in two years than dramatically excited for two months.