How to ask for design revisions: three examples from a poster
Way to turn the “a little more striking” comment into a revision note that the graphic designer can implement.

It's easy to say you don't like a design, but it can be difficult to describe why it doesn't work. You don't need to draw the solution, though. What the designer needs to hear is which reader is stuck on which information. When you describe this, the next rehearsal answers a specific question rather than a new guess.
Three notes, three separate works
Instead of “make it bigger” write “I couldn't find the event time on the phone at first glance”. The designer can change the position without increasing the size. Instead of “The photo is wrong”, say “There is old packaging in the image, the approved product photo is in this file”. This is not a choice, it is information to be corrected. Instead of “the logo disappears”, add where it disappears: on the white print or on the dark phone screen?
If more than one person comments, collect them in one rehearsal. Adding the page number next to the red mark and the first two words of that line is sufficient. If two people want conflicting colors for the same banner, decide who decides before forwarding them both to the freelance designer. When checking the final proof, do not just read the marked areas. Enlarging the title may have pushed the address just below it down one line.