For many food packages, it is important that they are well sealed after being opened. There are already special bag clips available to buy, but clothes pegs can do a good job here in the household:
Clothes pegs as a seal for packaging
So that nothing is lost with many foods, you don't have to buy expensive special clips right away: just take nice colorful clothes pegs as a seal: e.g. for tea bags or cereal boxes. Looks funny and keeps it tight!
Read also: Freezing food without plastic
Photo by Sabine, meinhaushalt.at