As a designer I've witnessed some very wrong designs... you can see there was thought, good color choices, etc. Have you ever seen a Facebook post that is a jumble of consonants, it usually ends with you are one out of a bazillion that can read it.
Not true, a lot of great minds work alike. In the designer biz, we talk about how something reads. It is part of our culture and unique language that makes so many non-designers decide never to converse with us.
So-- if you decide to try a DIY design project- poster, sign etc.- or you get a proof to approve. Be sure to put it up before going to print. Distance yourself both time-wise and physical proximity.
Leave your design open on the computer, or print a draft and casually glance at it while strolling by on your way to grab a cup of coffee. This extra step has saved many a design. Make it a RULE- that becomes a good HABIT!
Both images are examples of good intentions, bad layouts.