One tip is on the passangerside is to remove the two heater hoses from the firewall. Loosen the hard heater line from the intake slowing the heater line to move a bit. Take off the fasteners and you should be able to wiggle it out. Driverside is cake. Dont over tighten the covers when you put them back on.
I did valve springs recently. A priceless tip I found here for the passenger side is to rotate the engine until the last rocker arm in the back on #6 is down and it gives you just that little extra to get the valve cover out. I used a socket on the alternater pulley to rotate the engine. Think I may have had to rotate it counter clockwise but the nut did not come loose. Much easier than trying to rotate the engine down at the crank.
After a few HGs or pulling the motor, covers are as easy as changing the air cleaner
I use "the right stuff" sealant from AZ, along with cork valve cover gaskets.