You'll start on top of the plane with an RPG launcher. Just shoot at the Surface-to-Air Missiles marked on the ground to protect the plane. Once you'll get thrown off the air, glide to the checkpoint and deploy your chute. Once inside the cave, use your grappling hook to traverse the landscape quickly and climb the steep cliff efficiently. Kill the militia to save Mario and trigger a cutscene.
Join Mario for a ride and rush through the militia checkpoint. They'll be pursuing you so keep driving until you lose them and eventually reach the other rebels. Get out of the vehicle and start killing the enemy soldiers in the area. Once cleared, you'll get to your next objective.
Ride the chopper and fly to the next location before the timer runs out. Land/crash your chopper and take out the initial wave of enemy soldiers. Once done, grapple to the tower and use the mounted mini-gun there. Take out all the enemy vehicles until the mission is complete.