f you wish to appear a little more self-effacing use this as a first response:
"I almost always succeed because plan and manage accordingly. If something's not going right I'll change it until it works. The important thing is to put the necessary checks and contingencies in place that enable me to see if things aren't going to plan, and to make changes when and if necessary....."
or
"There are some things I'm not so good at, but I'd never say these are weaknesses as such - a weakness is a vulnerability, and I don't consider myself vulnerable. If there's something I can't do or don't know, then I find someone who can do it or does know."
Do you see the positive orientation? Turn it around into a positive every time