These activities, making use of flashcards (Why Use Flashcards?) will help you establish and remember the connection between the individual sounds and letters. After the first time you work through the cards successfully, you should go back periodically to review them. First review every few days, then every week or two. Even if you forget some of them each time, the act of remembering will strengthen your ability to recall them.
If you are using a Spaced Repetition System (SRS) flashcard program (for more on SRS, see: Resources for Making Flashcards), it will take care of the scheduling for you.