Does the motor turn over by hand? If not you need to get some ATF,and or Marvel Mystery oil in the chambers to loosen the carbon.If so I would still maybe put some ATF in the spark plug holes,and turn the the engine by hand. Get yourself a new set of plugs,but wait to put them in yet. I would disconnect the ignition,and crank the engine by the starter for a little while to get the oil flowing. Some 2-cycle oil in the fuel tank will help lubricate the seals before the oil injection pump gets oil flowing through the lines.
Oh yeah change the oil,and filter before all of this. I would also change the coolant as well. Make sure the battery is good and strong as the rotary needs to spin pretty fast to get started. It wouldn't hurt to clean up the battery terminals,and the connection of the ground on the motor,and body. The stock cables are aluminum,and corrode pretty fast.
If you get it running I would let it get to operating temp,and then shut it down. Then change the oil,and filter again,and install the new plugs.
74 RX-4 Hardtop
78 RX-7 GS Spark Yellow
74 REPU Lawn Green