Ensure that they are out of reach of their mouths [for lack of better word] first--upon a table or counter if at all possible for your stickers and art, and close to the ground or to the surface being cleaned for your hair.

Alternatively, there is the option to keep the suction on the lower side, is there not? It may take more time to clean, but I imagine you'd have greater precision if you kept it to that.

[There are the nozzles too technically, but he's still trying to figure out the best way to get those on and off and use them without wrestling the damn thing]