Give that baby your undivided attention and set a playful tone.  Your baby will see that you are focusing on him/her and will try to play with you.  Their eyes light up and they get excited.  Mama or Dada is playing with me!  Use signs that he/she is motivated to learn.  If you are playing with a ball, use the sign ball and give/take the ball between each other.  Do the same with other toys or even a stuffed doll.  Use every day objects or foods that are around you.  It makes a difference when you take the time and make it fun.  Sets the foundation for future learning and engages your child in social interactions.