QUOTE(Fantasia in P major @ Aug 14 2009, 01:48 PM)

Lizbun and Pushpull, I've been reading on another topic where you had mentioned you practised for 2 hours a day, and 1 hour a day respectively and I wondered how you managed it without causing your lip muscles to ache?
Well when I started 10 minutes at a time was seriously all I could do. I've built up gradually over 18 months, playing (virtually) every day. A 1 hour session is usually fairly comfortable now and with a gap I can manage a couple of sessions a day if I'm in the mood. I'm looking to up my workload now and I reckon I could manage 1.5 hours, though it's better to split up into 2 or more shorter sessions a day.
Reeds matter. Don't play on something that is too hard for you, it's counter-productive. You'll tire quickly and you will start biting down. I currently use Fortay reeds and they recently sorted out a few purple and blue reeds at the softish end of M/S for me (difficult to do, I know, if you're not there to try them). Even so, not all reeds are identical and I know which ones I can play longest on. Try to play on as relaxed as embouchure as you can get away with, especially on the lower notes. Your tuner is one way of telling you if you've had enough. If you're anything like me, when you start to tire your pitch will head skyward and become hard to control.
Do you do plenty of long notes? They're very good at building stamina as well as improving tone and tuning.
Relaxation is vital too. Take care to relax fully before you start to play, breath in a controlled manner, keep your shoulders down and hands soft. My first teacher said "you don't need to squeeze the notes out". Tension anywhere in your body has an uncanny way of finding its way to your lips.