Don't bend forward with knees straight.  This applies to both standing and lying positions.

If you have problems tolerating standing or sitting straight up, avoid arching the back or neck.  If you don't have problems in these positions, then try arching with some caution.  If it doesn't seem to bother you, then don't restrict arching.

When lying on your back, keep your knees bent.  This will help take some of the pressure off the neck and low back.

Avoid the "on all fours" position as this will put allot of strain on the neck.