Your infant should come home from the hospital in a Federally approved car seat and always ride in one from then on. Children who start out in seats as infants are much easier to keep in seats as toddlers. Be Consistent - Always buckle your child. Not using the restraint system because you are only going a few blocks confuses the child. It introduces an option the child can not understand.
Children learn from consistency.
Use Words - As your infant turns into a toddler and starts using language, explain in simple words why he must be restrained. Show him with a doll what happens in a crash. Set an Example - Children want, more than anything, to be like adults. If adults they adore are consistent users of belts, then they will try to be like them. Show them that you are buckled also.