Re: Servicing an old Alfa ?
Do the plugs one at a time - this way, you cannot mix up the plug leads.
A bit of copper grease or anti-sieze compound on threads of sparkplugs is always a good idea. Alloy head, you see. And as stated previously, make sure you thread plugs in first by hand, so as to not cross-thread the plug threads in head. As David J. said, don't get carried away tightening the plugs, either.
Have a look at plug leads at same time, you are looking for cracks in the insulation.
And spare a little time to look at the cooling system - you are looking for frayed fan belts, spongy rubber hoses (top and bottom of radiator), and heater hoses in engine bay. A split in one of these can really ruin your day on the side of the road...