Start with a clear character idea
A selfie, pet, mascot, avatar, or original character gives the generator a stable subject. The more recognizable the subject, the more cohesive the pack feels.
Ask for a usable expression set
Great packs include daily replies: hello, thanks, surprised, sad, angry, happy, laughing, sleepy, thinking, and celebration.
Review the whole pack, not one sticker
A single beautiful sticker is not enough. Check whether the pack has consistent style, readable faces, useful captions, and enough variety.