My items keep on getting rejected because they don't meet the quality requirements?

How do I ensure that the products I make are of the minimum standard and how do I make sure that it will not get rejected for this same reason again.

Make it the same, or better, quality than competing items in that category?
Hard to really give you specifics without knowing exactly what categories and which marketplace you’re talking about.

The category is in buttons under CSS. The problem is, the reason for it being rejected is very vague. I’m not sure weather it is the product itself, the Read Me perhaps or something else. After looking at some competing products, I have no clue why it got rejected.