Making sure that the temperature is at the right general level for a particular tea is important, as is water quality and of course the quality of the tea itself.
However, it is also important to remember that time has a great deal of impact as well. If a tea is not given enough time to infuse properly, the result will be thin, weak or simply lack any flavour at all. Likewise, if it is left for too long, the infusion process will draw out bitterness, excessive astringency, overwhelming tannins or other overpowering flavours that take over and impact the quality of the tea.
In general, most teas will need between two and four minutes to fully infuse. The best thing to do is taste test to decide, and to make sure that a customer has some control over the strength of their infusion. Depending on which teaware options you have gone for, this might be by having a removable infuser as part of the teapot, or by having a separate vessel to decant the teapot into once the tea is ready.