You should practice talking to the audience, just the same way you practice playing and singing--you decide what you want to say, where you want to say it, and work out what you are going to say, before hand, and stand in front of a mirror, or even stand up in front of all the furniture in the living room and pretend that there are live people out there and talk to them--

If you don't have a knack for speaking "off the cuff" don't hestitate to write things out and memorize them--many performers do this, even comedians who have a reputation for being "spontaneous"--

If you think that it is not important, because you are really just singing and not doing a spoken performance,think again--Unfocussed rambling, awkward pauses, nervous laughter and, especially, inappropriate remarks, can spoil a musically great show, and can make you look like you don't know what you're doing--