This video explains ways to elicit a correct /s/ or /z/.

This video is helpful tips on using a lazy "t' or evena lazy 'th' sound to correct lateral airflow that causes a distortion for /s/.  Specifically this therapist shows you how to use the 't' to help elcit straight airflow for /s/.

This video shows some tools that are used in speech therapy to elicit the /r/ sound.  

This video demonstrates some of the exercises your child will do in speech therapy to elicit and practice the /r/ sound.