what should I do before I try to start a vehicle that has been sitting for six years.

you could try removing the spark plugs and squirting a small amount and only a small amount of oil inside if the bore is dry and then wind it over by hand a few times. this shouldn't be too hard to do with the plugs out. after that, try cranking it over with the plugs out to expel any oil on the top of the pistons. if you put too much oil in with the plugs in, you could stand the chance of bending a rod.