I've got my first real gig coming up Saturday so any advice on 'use better technique' are just going to be wasted on me, it's a 2 hour set and I keep finding after the first hour my voice tires out and I've got no access to my head voice after that. Any practical tips to help rejuvenate myself in the set break, I find a warm drink helps but I won't have access to a kettle or anything.
>Gibson & Schecter Guitars
>Orange Amps
>And some neighbours to piss off
Drink a lot of room temperatured water and keep away from sugary and alcoholic drinks. Trust me, even if you are going to sing Slipknot (your username), please do not drink any alcoholic drinks to get more distortion.
Warm up BEFORE the show, sing along with a piano going through basic scales and triads in a comfortable register. It's very important that you do not strain at all in the warm-up, it has to be very easy for you.
Iced tea with lemon works.

Not to be a dick, but if you're voice is getting tired out in under 60 minutes, you should try a different technique. If you're new to the whole thing, it's just a matter of training generally.
"I think, as a musician, you should practice your technique to be as good as you need to be to facilitate whatever ideas come into your head."
- Devin Townsend
+1 on kris suggestion...I´d stay away from iced tea though....cold and sugary is not good.....we do 3 hour long gigs and it´s a strain this is what i do

*practice (regularly.....how often does the guitarist practice.....so should you)
*eat lightly prior to show...you need energy but not to be bloated, makes working from the diaghram hard.
*no milk 3-4 hours before show....not good for the old chords
*luke warm water before and room temp. water during gig....alcohol is for amateurs and everyone else not driving the bus home.
*work your set list according to the diffuculty of the song......don´t try to end on your biggest songs that you need to strain yourself....those should be 4-5 songs into your set when your voice is warmed up...
*warm up before gig...mouth and vocal chords...tons of videos on you tube. I also always have a harmonica with me just too exercise breathing....people alway´s forget to practice the breathing before gig and if your out of breath you can´t sing
*exercise.....this is no quick fix but it helps in the long run
*get your singing technique down pat.....if every song is exausting your either doing it wrong or in the wrong key ;-)

hope this was of some help//

I believe in god, jesus and the holy ghost.....or as i call them Angus, Kirk and Lemmy