Don't put alot of torque on the outer end nuts, and DEFINITELY don't put alot of torque on the center "acorn" nut or you will find that stud coming out with the nut next time.
Make sure that the mating surfaces are CLEAN. You could put a bit of sealant on ONE side of the gasket - usually the valve cover side - so the gasket will stick to it but still be easily removable from the head. Usually one can get away with this method for a few years before the gasket requires replacing - they do harden and shrink a bit with age.
Another option is to get the thicker, squishier silicone gaskets from realgaskets.com. If the head or valve cover surfaces are just slightly warped, the thicker squishier gaskets can take up the slack. Just be aware that they are thicker and squishier so don't overtorque the nuts putting them on.