Every individual has his or her own style when writing in a planner. After all, making your page look the way that you want it to look is one of the most important aspects of a planner.
When I write freely on a page (as opposed to using a form or custom design), there are three simple tricks that I use to maximize the ease of reading and using my page.
The first (left) column is for MUST DO tasks while the second (right) column is for SHOULD DO tasks.
Clouds for FYIs
I use a simple cloud drawing to indicate information only.
Box for Others' Stuff
I draw a box around things that I expect the kids and my husband to take care of, so that I can track it, but ignore it when deciding on my next tasks.