One of the toughest decisions you have to make as a leader is to say no. Sometimes you'll get a request that you know you can't handle. Instead of delaying an answer or saying you'll think about it, if you know the answer is a no, say it. It does no one any good for you to prolong giving your answer.
The other thing is owning up to mistakes. It's somewhat natural for humans to try and justify or come up with excuses. But as a leader you don't have such luxury. When you mess up just admit it as much as it bruises your ego. Honesty is always appreciated and valued.
As a leader you need to know your limits. When you are in over your head, admit it. If you know you're about to crash, confide in someone or your team to help you deal with it. Don't try and juggle it all by yourself. Sometimes your team members can actually be of great assistance in reducing your load. But if you don't tell them how will they know you need help?
Another tough decision you'll have to make as a leader is to take a risk on a new person whose capabilities you're unsure of. Great leaders know their team, but there are times when you're going to have a new member who you don't know well. Taking the risk to assign them with a task is tough, but a decision you have to make nonetheless.
It's not an easy job being a leader. But knowing what you might have to face in the future gives you the chance to prepare for it.
Saying no
Owning up to mistakes
Admitting you're in over your head
Take a risk on a new person whose skills you're unsure of