What Sadie said - I try to clip in as I'm going into the downstroke on that side. That way I have the motion of going down/forward already so it's just a matter of clipping the foot in. I start with the clipped in froot in the up or 12:00 position so I have the full rotation to get the bike going and/or get the other foot clipped in. Another thing you might look at - are you trying to clip in while standing or seated during take-off? I used to try and clip in while standing and I kept sliding off the pedal. Now I sit down on take off, clip in and then stand. Hope this helps!