How much leverage is safe in crypto?

I am coming back to trading after a break and trying to get my risk settings right before I size up.

1.) Is there a sane number for leverage, or is 2-3x the realistic ceiling for most people?

2.) Does it matter more than position size, or is the leverage number a kind of distraction from just sizing right?

3.) For anyone who's survived a few cycles, what rule keeps you from blowing up?

Thanks 🙏