When you receive a bouquet, take the wrapping paper out and give all stems a fresh 45 degree cut
Place stems in cold water. Make sure there are no leaves in the water. Change water every day, wash the vase and always cut the stems a little bit before putting it back.
The vase shouldn't be too tight or too tall. Cut off the flower tape to loosen up the stems, it gives the bouquet more space and air around.
Don't place flowers under direct sunlight, close to heating areas and fruits.
Unless you buy a bunch of same flowers, the blooms will age with different speed. If you notice some of the flowers getting tired, take it out from the vase and rearrange your bouquet to keep it fresh longer.