I was looking at the Self-Development Question for this week:
"How do you make predictions about your life?" "自分の人生をどうやって予測しますか?"
It might be suprising for you, but in my case, I use a Japanese Omikuji Calendar, that is based on my date of birth.
驚くかもしれないが、私の場合は、私の生年月日に合わせて 日本語のおみくじカレンダーを使っています
There is a short comment for each day. For example, my luck in business, personal relationships and in money. And my lucky color for that day. It's fun to look at, but I try not to take it too seriously.
You know, it's an interesting question, and you know, it's not really an easy one to answer. That's two examples of how to use "you know".
"You know" has many different uses - mostly it is just to "fill in" the space between the "real words". (言葉に詰まったとき) For example, えー、ほら、あの…、ねえ
Other times it is used when you want to make sure the other person is paying attention to you. For example, あのね、あのー、ねえ、ところで
And of course, it is also used as an informal way of saying, "Do you know..?" or whenever you think that the listener already knows what you are talking about, for example: 知っているでしょう。
I hope that helps. Let me know if you have any other questions.