What's the difference between confidence and presumption when it comes to God's provision in risk-taking?
Let the Bible give you whatever criteria it can in whether or not you take risks for Christ. So whatever the Bible forbids you to do, don't do. What it commands you to do, do. So that's the first place to start.
Then let principles hold sway. Jesus was very hesitant—I mean, absolutely did not jump off the temple. Satan wanted him to do this radical, dangerous thing: "The angels will catch you and God will be glorified." And Jesus saw it as a ruse. The devil didn't want God to be glorified through his taking that risk and being rescued. And that may be the case for you as well.
So I think part of that right there would be, "Is my motive in order to attract attention to myself as a risk-taker, and to get some honor for how valiant I am? Or is there a need right now that I've got to jump in to, and I'm not going to let fear stop me?"
Those would be two very different motives, wouldn't they? The sense that 1) "I'm taking a risk and God's going to get glory because I'm such a valiant risk-taker" or 2) "There's a need here and a possibility that I can meet the need, and I'm going to overcome obstacles of fear to get there."
So I think motivations and biblical guidelines and constraints are the way you move forward.