Recommend on how to plan or what to plan?
Basically I just write down every thing that comes into my mind and write them. Its important to put date so that you will know if you're efficient in finishing plans or not.

Divide your plans into short and long term. Also mark it based on its value to you.

Most of my plans are about my career path. I'm a designer so my plan includes creating specific types of design for my portfolio and studying new skills.

Every morning, browse your notebook for some plans that you've missed doing.