I'm looking for some recommendations on how to work with our almost 4 year old on speech. There are some letters that she has a hard time with and I don't want to push her too hard but also would like to know the best way to help her learn how to say these sounds better. Examples: th comes out with the tongue out and L sounds like a Y.

We read to her daily (at least 4 books a day) and listen to audio books on the way to and from work. When she says something improperly, we repeat the word back to her properly and she usually tries to do it again.