Make communication easy so that communicating is motivating. At this stage of development it is most important to make communication easy for your child so that s/he experiences success when communicating. Once your child is successful at communicating, s/he is more likely to understand and develop more sophisticated ways of communicating.
Pick a type of communication for your child that is meaningful. If your child needs a lot of concrete visual information to communicate then use objects to help him/her communicate. If your child is able to understand pictures but has trouble using words, then use pictures. Your child will not be able to communicate successfully unless the form of communication that you teach, is a form that s/he can understand.
Your child's communication development is likely to be uneven. Your child might start communicating using physical movements such as taking your hand to show you what s/he wants. Then s/he might start to use objects, then pictures, and then words. At any point in this progression, however, your child might use more than one method. Your child might use words some of the time and pictures at others. If your child is using several different levels of communication you should respond to all of them instead of "holding out" for the highest level. You should model the type of communication you want your child to use but still respect his or her initial response so that communication continues to be successful and motivating.
The most important form of communication to teach is the form that your child will use spontaneously. If your child will show you a picture but will only do so when you say, "show me cookie," then your child is not communicating spontaneously. If this is the case, use an easier way to communicate and give your child lots of practice using that method. Teaching your child vocabulary words can be helpful. However, if your child doesn't use his vocabulary spontaneously, then the time will not have been useful. You will always need to spend as much if not more time teaching spontaneous communication than vocabulary. It takes more creativity to create an environment in which your child will communicate spontaneously. Your are, however, the best person to do this because you know your child well and are with him/her in many situations so you have many opportunities to encourage communication.