Type of Planner
What type of planner you use is up to you and what you are keeping track of. There are some that are detailed to the point of letting you note events on a half hour basis. There are those that only show blocks for each day in a traditional calendar setup. Find out which one best fits your needs. If you are unsure, try out a couple and see which one you really like the best.
How to Use It
You need to be committed to using this planner when you get it. Find out what works best for you in terms of how often to look at it. Personally, I think you need to start your day looking at it and end it doing the same thing.
Planners are great, but they can be something that takes control of your life. I’ve known several people who become obsessed with their planners. They become inflexible. While a planner helps keep you on track, you have to be flexible too. Life throws curveballs.