Don't over think it. In fact stop thinking about it and let it happen. That seems like the biggest obstacle for people with clipless pedals. It's really simple, make it become part of your muscle memory. I have no idea when or where I clip in, I just do it and it never occurs to me that I have.
Put your feet down and find the pedals, they're always in the same place right below you. Let your feet find the clip and bam you are in. It can and should be done with out thought.
oh yeah, make sure your cleats are tightened down on your shoes.