Do you have a skatepark nearby? Go there and try riding part way up a ramp like a quarter pipe, bunny hop right when your bike stops (not while your still moving forward, but make sure you do it before you start rolling backward too) and then fakie out. The bunny hop helps you to keep your balance because you're in the air instead of stopped in one place on the ramp for a second. If there's no skatepark near you then just find anything that resembles a ramp (driveway, smooth tree trunk, etc.)
"if you feel yourself falling backwards, thrust forward like you would if you were indeed fucking your bike, and if youre falling forwards, push your legs while leaning back, like if you were pulling out from fucking your bike But dont, under any circumstances, actually fuck your bike" - EddiMundo