Slice of life, to me is very much about showing the daily lives of your characters and showing their personalities. In my experience, writing good slice of life is hard but rewarding, as your characters have to carry the story. If your character isn't engaging/likeable/interesting enough, your slice of life will fall flat.
Another factor is emotions, character arcs and a good hook. My story, while by no means a perfect example, does this to make the slice of life style more interesting.
My main character is initially a somewhat whiny, sheltered church kid who is out on her own for the first time. She's a little selfish, idealistic and overreacts to people's criticism. The whole story is literally about her getting her shit together and figuring out who she is. It's meant to be relatable, funny, realistic and raw. While she never faces a big bad guy or saves the world, she's constantly conquering setbacks, bettering herself and maturing.
