What steps should I take in starting an old 78 lincoln town car that has been sitting in the garage?

That is tougher than it sounds. I would recommend do a shot of fogging oil in each cylinder let it sit at least a day, drain the gas from tank and carb, new oil, gas and oil and gas filter, sea foam, trans flud filter and change, air filter, plugs, points, distributor cap and rotor if applicable and spark plug wires, and battery, probably will need a starting fluid kick to start.