To improve the chances your plan will succeed, think through the details and create the conditions that will make it happen—ahead of time if possible.
If the batteries in your headlamp burn out on the trail and you didn’t bring extras, you’re in trouble. If you brought extras, but they don’t work, your still in trouble and you feel foolish. Test everything before you need it. Have a back-up. Test your back-up.
Anticipate mistakes and prepare for them. I keep an extra pair of hiking boots in my 4-Runner in case I forget to pack my regular pair. I’ve had to use them, too.
Prepare for the unexpected. I once neglected to bring a headlamp on a hike because I was sure I’d be off the trail by midafternoon. I was hours from the trailhead when the sun went down and the rain started to fall. I got back to my car at 3 am, whipped, wet, and wiser.
Pay close attention to the details. A friend of mine showed up at the trailhead with a pair of boots. But he brought two left boots. Fortunately, we were near a store that sold hiking boots. Now he has three pairs.
I have a friend who served in the Israeli army. He was taught to prepare not for what he thought the enemy would do, but for what they were capable of doing. In other words, prepare for the possible, not just the likely.