Avoid waste of time as life is small.
Just as I consider meditation quest, search, and explorations as the best utilization, and having the time of your life, quite a few things that we do are a waste of time, really.
The following are a few examples according to me, though you may write a different list according to your whim and understanding.
Socializing all the time
Spending more than necessary time on phone, Whatsapp, Facebook, Twitter, Internet etc.
Watching excessive cable TV, or movies
Listening to music much more than required
Eating a lot of junk food
Playing cards, video games beyond a certain limit
Talking and talking unnecessarily, or gossiping