If you have time, go to dogpile.com, and search for 'rubber seals and o-rings'. Pretty much go down the list requesting engineering tips and catalogs. Most will have basic specs in their literature. As for specifically applying to your face seal problem, my experience is with high pressures and brake fluid, so take the advice as it works for you:
1. keep all corners from being sharp, especially in the dovetail. The o-ring will roll like a torus under high pressure and peel just like a log in a plywood factory.
2. allow for expansion of the joint, and some extrusion of the rubber between sealing surfaces. (avoid thin wall sections on the low pressure side, as they will cut when the joint settles)
3. watch for chatter in the machined surfaces
4. Don't try too much overcompression of the ring, because you just end up with pinching during assembly. Let the seal do its job as recommended by the mfg.
5. Not necessarily least important, make sure the seal material is compatible with the local outside environment, not just the contained material.
6. Don't get too cheap on the cross-section size. Robustness comes after the seal starts to wear, not when new.
7. Watch your temperature recommendations. Feynman wasn't joking that time.
