An engine that has been stuck (even just the carb barrel) from sitting too long should be flushed out with fuel at a minimum. You want to get any accumulated dirt and debris OUT. I would pull the backplate and pour fuel in (cover carb opening with your thumb)... set the backplate in place and shake well... remove the backplate again and pour out some filthy fuel. If its really bad... repeat. Then bolt the backplate back on.

Bolt the engine back on the plane and DON'T attach the throttle control.

Too rich is always safer (for the engine) than too lean.

Close the air bleed completely then open it 1 turn (it will be too rich there)
(if it is not an air bleed carb... REMOVE the idle needle. close the main barrel, turn in the idle needle until it has slightly increased resistance or you see the throttle barrel get pushed by the needle (watch CLOSELY!) open the idle needle 3 turns)

Close the main needle completely and open it 3 turns.

As stated above... set the throttle barrel limit so it will open fully, and close down JUST completely. (maybe a small visible crack... but not much)

Now hook up the throttle control linkages. (I will assume a non-computer radio below...)

Turn on the TX and RX and verify the controls all respond correctly with no binding. Be extra sure of checking the throttle for full range. (include the trim tab in here... you want both the sitck and the tab at full for full open... both at minimum for fully closed.

Set the trim lever to full throttle and the stick to minimum. The throttle barrel should be appx 1/4 to 1/5 open.

Follow safe engine starting proceedures... (get help if you don't know them... the prop can take a big chunk out of you if you aren't careful.)

The engine should run. It may not run well or for long... but you just slowly close the main needle to make it run.

Carefully bring it to full throttle and tune the high end. You can't tune the low end until the high end is correct.

The low end should be set by slowly bringing the engine to slower and slower speed. You should be able to have it at a slow, stable idle with minimum main stick and just a bit under 1/2 trim. (carb open appx where a 1/32 square balsa stick could be inserted in the crack without scraping off any balsa) slowly open the air bleed , or close the idle needle to achieve this.