Having a second set of eyes helps a lot when working on things. Every now and then when I do virtual shows I’ll sneak a friend into the zoom and have them write notes on the show. Recently my friend noticed a rookie mistake I made.
In my three shell game routine (my Russian Shell Game routine) I have a graphic overlay pop up with the numbers 1, 2 and 3.

I wear a white shirt and the numbers are white. My friend pointed out that they blended into my shirt. It was a simple fix to add black borders to them for the future

Now they’ll work with pretty much any background.
Having a fresh set of eyes watch your show for little things make a big difference!