Most people would probably just turn the key and see what happens.
You can start taking the car apart, but you might not need to.
How old was the gas when you parked it?
Putting injector cleaner in the tank surely would not hurt.
One simple thing that may be worth doing:
You could disconnect the fuel lines from the injector ring and put them into a bottle. If they are too brittle to do this, they need to be replaced anyway. Put some longer fuel hose on temporarily to add flexibility in the location where you put the bottle. Turn the key to the on (not start) position, and the fuel pump should run for a second. Repeat as needed to see the condition of the fuel in the tank and to determine if your fuel pump is working.
You could possibly jump the fuel pump relay to make the pump run constantly and drain the tank if the fuel looks bad.
If you want to drain the tank, or if the fuel pump is no longer working, then you can drain the tank by removing the hose at the back under the tank by the fuel pump. This is more of a mess though. Once you start, it’s harder to stop, and you better have enough containers ready to go to handle everything that’s in the tank.
If you need to clean out the tank:
I’ve discovered that varnish remains as chunks when it is wet with fuel, but if you can completely dry it out, the chunks crumble to dust that is much easier to remove. With a removed tank, you can toss some rocks or nuts in there and shake the tank around to make sure they bang on all the locations to free up any hardened varnish, again, which is much easier to remove when dry.
If the fuel hose in the fuel ring is due for replacement, then this is the time to do it. If not, maybe you could run some concentrated injector cleaner mix through the injectors and run the car on an auxiliary fuel pump and tank. Bringing cars back from the dead all the time, not wanting to do the items above, I do this all the time. It’s easier having a rig with a pressure gauge ready to go. Here’s the last one I got running on a fuel pump rig.
https://youtu.be/hjR7I-fuMT0
That car hadn’t run in probably 20+ years.