Replenish the water frequently. Change the water every 2-3 days.
Trim at least 1cm of stem off your flowers before you put them in a vase after each time you change the water.
Keep your flowers away from heat and bright light.
Avoid sitting your flowers beside ripening fruit or vegetables, especially bananas and apples.
When the flowers are done, be sure to wash the vase/container very thoroughly in hot soapy water or, better yet, in your dishwasher.
Use “flower food” for most flowers