Write something useful for your readers. Share a relevant piece of information, an event update or a hack that makes a task simpler
Formatting - Your post need not be a circus. If you are not good with formatting, then stick to a theme that is light and descent in colors and the post layout. If you are good with trying new stuff then use that skill to better express through colors, fonts and layouts. Avoid colors that are dark and fonts that are overtly bright.
Use simple vocabulary. Important is to reach their hearts not testing their literary skills.
It was lovely knowing your takeaways from 2017. Now, let us hear your wishes for 2018. Aren't we all looking at the new year with love and hope? It is better to write down and then refer to it regularly if you really care about them.