Drink up to 8-10 glasses of pure water every day (any caffeinated drink does not count). Water thins your mucus and lubricates your vocal cords like oil lubricates a car engine. Thick mucous causes friction and trauma to vocal cords. More water, less friction, less trauma, better voice.
Warm up your voice regularly. Simple warm ups are recommended, especially for auditions and performances (just as runners warm up for a marathon). Better yet, take a classical music approach: do glissando's (descending scales) and staccatos (punctuated breathing exercises) and messadivoce (controlling intensity of volume).
Take vocal "naps". Your voice needs a rest, just like you do. So, find quiet time everyday - especially when on tour.
Get adequate sleep. Sounds like common sense -- and it is. The more sleep you get, the more you will be awake and have more energy for a show.
Do not smoke anything. No finger wagging here, it's just that smoke is an irritant that swells your vocal cords. And a reminder: New York bars are smoke free, so you can play in any venue without the damage of second hand smoke.
Use your microphone. There is no need to sing to the back of the room. Let the microphone be loud for you. Using the microphone prevents straining your voice.
Have good monitors. You need to hear yourself for vocal feedback. Use a floor monitor or ear monitor to be aware of what you sound like, what the band sounds like. You may be singing louder than you need and straining your voice.
Develop good singing technique. Vocal training will not change your style. It will strengthen your voice and allow you to sing longer, louder, more often and without tiredness.
Develop a speaking voice to go with your singing voice. You speak 99% of the time and sing 1%. A poor speaking voice often leads to vocal strain that will carry into your singing voice. This is true especially on tours, when giving radio and other media interviews.
Most importantly, listen to your voice. Like any athlete, you will be the first to know when trouble is starting. If you voice hurts, back off. Change your set. Chose songs you can sing without straining your voice.
If you would like any more of this helpfully just visit www.giftedvocals.com.