If you have a tendency to overthink things, to overcomplicate things…write it down.
By writing down your thoughts, it helps you to clarify them, rather than having those thoughts just running around in your head.
If you do not like to write, just saying your thoughts out loud can work the same way. Maybe record a short video of you speaking your thoughts.
And conversely, if you oversimplify things, or underthink them… read.
Do some research. Google it.
The more you learn about your topic, chances are, you will realise how much you do not know.
Replace overthinking with writing. Replace underthinking with reading.
NB: Credit to @wealth_director on Twitter for the inspiration.