Use The ABCDE Method

First, write down every single task you need to accomplish. Then go through and mark each task with a letter ranging from A to E.

• “A” tasks are very important. If they aren’t done, you and/or your business will experience serious consequences....

• A tasks: things you must do - they're your frogs. 
• B tasks: things you should do. Replying to emails or attending meetings are often should-do tasks. 
• C tasks: nice-to-dos. You probably want to do them, but there are no consequences if you don't.
• ...

• "A” items are most important: the things that you must do.
• "B” items only have minor consequences: tasks that you should do, but they only have mild consequences.
• “C” tasks have no consequences: they have no effect at all ...