I found some die cut letters at the dollar store and traced them onto a poster board so letters could be added on each letter day. Each boy has their own poster because I knew they'd fight over it. For my budding reader I found these lined strips of paper perfect for words and laminated them so the words could be changed each day and then I used dry erase markers for it. Easy peasy.
Point out letters on signs and billboards when doing errands
Have them practice writing letters in their homework books
Play the eye spy game with something that begins with the letter of the day
Pointing out packaging on food or books throughout the day
Trace the letters on their poster with their fingers
Doing other fun ways of writing letters (write it in finger paint, write it in shaving cream whatever you can think of)
Before going to bed doing a little quiz of the words of the day and review all the letters we've done