Read Aloud Alphabet Book
Have multiple books that involve the alphabet to your young child. Reading multiple stories aloud that include the alphabet will expose you child to the alphabet more often, which will have them learning the alphabet and the sounds of letters sooner.
ABC Toys
While children are playing on the floor or with their toys, make sure there are plenty of ABC toys that they can play with and mess around with. Once recommendaton is to have the alphabet floor mats that the young children can roll around and crawl on and while they are playing with their toys they are seeing the alphabet all of the time.