I sat on my bike in the backyard, one foot steadying myself on a stair tread and practiced clipping in and out with the other foot for five minutes. Switch around and practice clipping the other foot in and out for five minutes. Then, clip in and rode to the gate, slow down to open it and forgot completely that I was clipped in. Down I went. Went back for more practice, fell again. Said F' this, got my regular shoes on and rode the bike around the neighborhood on the platform side of the pedals.Now I ride clipless just fine. I think it's just a matter of staying vigilant until muscle memory develops that includes twisting your foot before setting it on the ground.