Change the gas in the tank.
Change the Oil
Flush and fill Coolant
Pull all the spark plugs and put about a Tbs of Marvel Mystery Oil down each cyl.
Let that sit for a bit
Spin the engine with the plugs out, I use a long pullbar on the crank at the front of the engine
Put back in the plugs
Crank it. (It will smoke like crazy until the MMO is burned out)
After it runs a bit, I would then change the oil and flush the coolant again.