A simple list:
Spend no time planning
If you forget to plan, you are planning to forget.
Spend too much time planning
Masturbatory planning can be fun, but it accomplishes nothing.
Let the planning tool do the work
Even if we had artificially intelligent planning tools, they still wouldn’t want the same things for our lives that we do. You need to do the work. Some friction in your tool is healthy.
Make unrealistic plans
This is an easy way to avoid doing actual work. After making the plans, you maybe get a step or two into them before giving up and going back to make new unrealistic plans.
Make easy plans
This can be a really good strategy if you don’t have confidence in your ability to get things done. But if you stick with it for too long, you’ll just get to the end of your life and only have your impeccable record of flossing your teeth to be proud of.
Get stuck in ruts
We need some chaos, disorder, newness in our lives. Not always, but sometimes. If you feel like you’re stuck in a rut, change something. If it doesn’t help after a week or two, change something bigger.
Be dogmatic about what worked in the past
Dogma makes religions stronger and individuals weaker. If you did have a period in life where you were very productive, you might be clinging to something you thought worked. If it isn’t working now, you still need to change it.
Chase every new fad
There are regular planning fads: 7 habits, GTD. They wouldn’t be fads if there wasn’t deeper truths, but it can be hard to sift the truth from the cruft.