Source
Digital flashcards! (Best on a PC)
Recomended method of use:

1. Select one or more groups of letters, numbers, syllables and or words that you want to practice.

2. Try to guess the sound (if you can) and say it out loud. Then click on the card to hear the sound and see if you got it right.

3. Once you feel like you know them pretty well, change your selection and keep learning.