Plant mines and fake mines. Set them off to kill the maximum number of Russian invaders.
Throw Molotov cocktails at all of their unguarded equipment, especially food, ammo, and fuel supplies.
Destroy Russian invaders' equipment anyway you can (sugar in gas tanks, nails in their tires, anything to show that Russian invaders that they're hostile takeover by the Putin dictatorship is unacceptable.
Do whatever you can to drive up the cost in money and material to this unnecessary assault on a weak and poor nation.
Use snipers to kill Russians but avoid any pitched battles.
Feign cooperation and then poison Russian invaders food and water.
Lure Russian invaders off task and kill them anyway possible.
Always use your imagination to raise the cost in men and materiel of the Russian invaders.