I have a 3 and a half y/o son with unilateral cleft lip/palate. He has been in speech therapy for almost a year.
His therapist stresses repetition! They work on 1 letter for a week or two. The therapist also made games out of a lot of it. She made picture cards of things and my son would have to say the name of the item and then he gets to do something (his turn at a game or sometimes she just had a board with velcro and he'd get to put the card on the board). For both F and P she encouraged him to make the sound more forceful by having him "blow" a cotton ball or feather when making the sound. She also makes sure he watches her mouth when she says something she wants him to repeat, we do this too.
My son loves music so we use that too, he sings alot of songs.
We have a way to go yet but I have seen alot of improvement. He says most letters well except for S (I'll take any tips there).
Hope this offers you some help. If you want to email me you can at:
mrskuroos@ivillage.comJill