There is a saying that the pot is the father of the tea, but water is the mother - the quality of the water is very important. If you use tap water, filter it. Tap water is chlorinated and can alter the subtle flavours of tea. Always remember to use fresh water each time you boil the kettle, as each boiling reduces water's oxygen levels.
PLEASE DO NOT POUR BOILING WATER STRAIGHT INTO THE POT!
It scalds and "stews" the tea, so when the kettle has boiled, let it cool for a time dependent on the type of tea.
Black teas, pu'er, rooibos and honeybush should be steeped in freshly boiled water. Green teas and white tea should be brewed in water that has been boiled and then allowed to cool for two minutes or more - the more delicate teas, the cooler the water.
Personal taste varies so experiment with each tea. Also teas in bags will infuse quicker than leaf teas, as leaves in bags have a greater surface area.
With quality teas, water can be added 2 or 3 times, depending on the type of tea. Each infusion brings out a different quality of the tea.