How to Brew Tea

Having written several long articles about brewing, I should summarize my understanding.

1. Control the amount of leaves

Leaf-to-water ratio

Let me first define this concept. I only share my understanding; if it differs from other teachers', and if you learn tea from me, I suggest you listen to me for now.
Example: suppose an empty gaiwan weighs 100g, and filled to the normal brewing level (not overflowing) it weighs 220g - so the capacity is 120g. I recommend a leaf-to-water ratio of 1:20, which means 6g of leaves (120/20=6).

The key to controlling leaf amount is habit. Many who come to learn from me grab leaves by hand without a scale - and the foundation of brewing good tea is gone. How can you learn tea well that way? I tell them repeatedly, and they try, but as soon as I do not remind them they grab by hand again. Guessing by eye does not suit the learning stage.
Learning tea is a process of self-discipline; habit is muscle memory that must be trained and held to strict standards.

2. Control steeping time

Drinking

For normal drinking, I use these times:

First steep: rinse, fast, 2-3 seconds.
Steeps 2-5: fast, about 5 seconds.
Steeps 5-8: medium, about 10 seconds.
Steeps 8-12: slow, about 30 seconds.
Tail water: from 60 seconds; beyond 20 steeps, from 2 minutes.

This timing starts when the lid is put on after pouring water. Adjust to your own taste.
Some teas release very fast (e.g. broken leaf) - steep shorter. Some teas, like dragon balls (longzhu), can take a slightly longer rinse and a wait until they open up before brewing begins.
When you start learning, buy a stopwatch.

Tea tasting (evaluation)

One of my main jobs is tasting tea, so here is my routine for reference:

First steep: fast, 2-3 seconds, rinse.
Fast, about 5 seconds, two steeps, drink normally.
Heavy steep 1 minute, taste the heavy liquor.
Heavy steep 3 minutes - usually not drunk, pour out.
Heavy steep 5 minutes - pour out, not drunk.
First tail-water steep, 30 seconds.
About a minute per steep; drink 2-3 tail steeps.

Normal drinking gives you the everyday taste. Heavy steeping acts like a magnifier, intensifying flavor to reveal strengths and flaws. Tail water tests endurance, whether the tea falls off to water, and hints at ecology and tree age.
When I develop a tea - especially blends - I test with gaiwan, pot, boiling, even distillation, and leave brewed leaves overnight to steep again next day. Every vessel and every method must be tried and verified before it passes.

Suggested gear

2 gaiwans, 2 pots (one big, one small), 2 sharing pitchers, a dozen tasting cups, one kettle, one small scale, one tea pick, one tea caddy, and a sterilizer.
That is enough. You do not need a dedicated pot per tea - I use one pot for every tea and find no flavor mixing, as long as it is washed clean each time.
Ordinary versions of all of these suffice; no famous makers or handcrafting needed - unless you have special requirements or personal taste.

Summary

Brewing tea is about precision and simplicity - do not let non-tea factors interfere.