myversa

Depends on what kind of bf/gf you have.  

If he/she likes to watch movie, bring him/her to watch movie.  After the movie, you two can discuss about the movie.

You can start to ask him/her questions like "how is the day and stuff" and maybe he/she will start to talk about her day.

If he/she is not in the mood to talk, you can tell him/her jokes or stories or stories about your past which might trigger him/her to start talking.

However remember if he/she is too tired to talk for the day and does not want to be bothered by anyone, just leave him/her be.  If you FORCE a conversation, it might anger him/her.