Making good tea requires technique and proper tools. There are many things can affect the quality of your tea. Here are the most influential factors:

The quality of the tea leaves: If possible, try using tea leaves for your tea because you can see the quality of the tea leaves. Good teas are a bit expensive, but since we can brew the tea leaves several times it is worth paying a little more.

The quality of the water: Water quality also affects the taste of your tea. Avoid hard water or salt water. I always bring my own water if I need to make tea somewhere other than home.

The water temperature and brew time: I normally recommend not to brew tea
longer than one minute when using a small teapot. Depending on what type of tea you are brewing, adjust the water temperature and brew time according to your preference.

Here are my recommended water temperatures:
Green tea: use water temperature of 80° Fahrenheit
White tea: use water temperature of 85° Fahrenheit
Yellow tea: use water temperature of 85° Fahrenheit
Oolong tea: use water temperature of 90° Fahrenheit
Black tea: use water temperature of 95° Fahrenheit
Puer tea: use water temperature of 95° Fahrenheit

The quality of the teapot: A good clay teapot can enhance the tea flavor. But is it not easy to find a good quality and food-safe clay tea pot at a decent price. Since beginners may not be able to tell the differences, using a glass or porcelain teapot will work just fine.

Amount of tea leaves to water ratio: 1g of tea leaves to ~20ml of water.
Depending on the tea and personal preference, the ratio can be adjusted.

Brew: Light color teas can be brewed up to three times while darker color teas can be brewed up to five times. Good Puer teas can be brewed at least 10 times, and still have a strong, aged tea aroma.