Won't start, then will!!

I was driving my 68 to drop of the kids, about 15 mins. Went in dropped them off came out to start the car heard a click and then nothing. No noise when turning the key again. The lower right idiot light cam on but nothing else. Tried a few times and nothing. Got out and wiggled the wires around in the engine compartment, could not see anyhing loose. Tried it again and nothing. Waited a few minutes then tried it again and it started right up. Ran great to work(30min) and home in the evening. Went out to start it this morning and the same thing happened . What do you guys think it could be and where should I look first?
Thanks for the help