posture

When I played sax the first time around I was in a school band and we always played seated. I found that with the length of my tenor sax combined with my short height and the uniform long skirt there was no way to play seated other than to twist the mouthpiece a bit and play with it against the outside of my leg on the right hand side.

Now that I am coming back to sax and can play however I want (sitting or standing) I'm wondering about posture - what is good, what is bad. I still feel like playing with the sax to my side even when standing as when I put it in front of me and hold it out from my body even a small way, I seem to have to tilt my head back to get my mouth onto the mouthpiece. I have had trouble with my neck from office work (doing 12 hour days in front of the computer) and now my neck is very sensitive to posture and muscle tightness and I can get headaches that last for days if I get things wrong. So I want to try to get my posture right with my sax straight away.

Can anyone advise on this? I'm especially interested in hearing from other people with neck problems and how they cope/compensate.

Thanks