Just look at what's in there now, that catches your eye. To me anything that is colorful and "exciting" typically gets a look. However, it has to be something I am interested in also.
For instance, in the Google Play App store front page now, at the top in the scrolling tiles section you have Pocket app. The tile is boring. You can't tell what it is just by looking at it. However, Color and Draw as well as NBA Jam looks colorful and you pretty much know what you got. NBA Jam looks exciting.
I would think that you would want to "sell" your item from the first moment that someone sees the icon (or tile in this case). I like apps that are obvious what they are from the moment you see them. Something that catches the eye in the ocean of other apps. Just my $.02