I have a 69 camaro that has sat for about 20 years garaged.. need suggestions on what i should do before I try to start it up or turn it over.. thanks

I would drain and flush the cooling system, drain the oil, put in 4 quarts oil+1 quart of Marvel Mystery Oil, pull the plugs and squirt some WD 40 into each cylinder, turn the engine over a few times by hand, change the fuel filter, clean or replace plugs, dump a couple tablespoons of gas down the carb, and start it up. If it runs let it warm up and change the oil just like the first time. If it doesn't run dump some more fuel into the carb (NEVER dump gas in while cranking as a backfire could result in disaster) and try it again. You might need to flush the fuel system to get it to run on its own. There will be lots of things to check after you get it to run. Things like hose conditions, valve adjustment, drive train gear boxes flushed and refilled, etc. Let us know how it turns out.

Welcome to the Club to both you guys. Before starting, you may also want to remove the fuel filler cap and smell for stale fuel. If evidence of stale fuel, you may want to provide a separate gas can of fresh fuel and a long hose from the can to the fuel pump. Fuel pump may have a cracked diaphram meaning the carb will have to be
gravity fed from the gas can.

I'm sure if its been sitting for twenty years, fuel has soured. However, carb may be in the same condition, needs removal and cleaning. Later, drop the tank, send it out to have it cleaned at a radiator shop. Using a siphon air gun, run a gallon of alcohol through the fuel line, disconnect from the fuel pump.

Remove the air cleaner assembly and you will notice a 1/4 inch dia tube sticking up. This is the bowl vent tube. Pour the fuel through the funnel into the bowl vent. Maybe a fourth of a cup.

You might consider pulling the distributor and priming the engine oil.

Good luck in your adventure.

How do these people find stored cars? I know, take leads from friends, drive through the countryside, hit the obituary page, etc.

OBITUARY PAGE?

....survived by a son, David, age 51, and a Camaro, age 35....

Oh yeah.... many a car has been sold before the lawyers get ahold of their estate by cruising the obits.
That's how I got a MINT 30,000 mile '65 Belvedere in 1986. Opened the garage door and thought I was looking at the car in a showroom!