Design for the size it is actually seen at
Shrink the draft until it is a postage stamp. If you cannot tell what it is, start over. Big face or big object, two or three words, a background that is not the same color as the text. Curiosity is a question the title does not fully answer, not a lie.
Keep a series looking related: same type, same corner, same color. Then test. A thumbnail you love and never compare is a habit, not a result.