Honda Accord has been sitting for 6 years. Where should I start doing first to get it running again?

Throw a battery in it, check the oil, antifreeze, and then see if it turns over, see how much gas is in the tank, if it is more than 1/4 tank you'll want to siphon that gas out. If it is less than 1/4 tank, fill it full and add a bottle of Sea Foam(if it happens to run, run sea foam in the gas tank at least 2-3 more times to clean the fuel system). If it starts, good, if it does start and run you'll want to change the oil in it ASAP as well as the antifreeze (have it flushed). If it doesn't start, you'll have to start by seeing if it is getting spark, fuel, etc....

Replace the battery Drain the gas tank...and rinse it out. Watch for debris as you do this. - I had a van that sat for 3 years...had to drain 15 gallons of gas, but it was a plastic tank and had no dirt or debris at all Change the fuel filter, change the engine oil & filer, check the air filter. Replace the transmission filter and fluid. Some people recommend removing the spark plugs and giving each cylinder a squirt of penetrating oil. Inspect and change spark plugs, wires, ignition components as needed This should get you going, but you may have issues with gaskets and seals drying out and cracking, particularly in the tranny....Good Luck.

After putting several abandoned cars back on the road I would strongly suggest not trying to run any of that gas still in the tank through the car. That shortcut has come back to haunt me several times. Draining the tank will let you check for solid residue in the fuel and remove all the water. After all those years you have no idea of how much water has condensed into the tank. Why take a chance on ruining 10 plus gallons of good gas to try to save a couple gallons of bad gas. I drain those old tanks, filter the old gas to remove solids and water, then mix it 1 old to 5 new gallons and burn it in my garden tractor or other vehicle with carb.