For me the climbing was the the "ah ha" moment! But I feel your pain though, I just switched from MTB pedals to Road pedals and I'm having a hard time learning to clip in after a stop light.
I was having issues with numbness too. I had two solutions
1. Loosen my shoes. This took care of about 75% of the numbness.
2. When I'm on a flat I just pull up with my legs for a minute and wiggle my toes, this allows blood to flow back into the nerves in my feet. I do this about every 5 miles or so. Just like you have to get out of the saddle once in a while to get blood back in that area or move your hands around your feet are your third point of contact with the bike and they need a break too.
Stick with them, in a couple weeks you'll wonder why you waited so long to go clip-less!
Good luck!!!