[header] How to pronounce words clearly with a lisp [title] Smile. [step] Looking in the mirror, open your lips like you're smiling. When you begin saying the sounds, you'll want to keep your lips open like this to be able to see your teeth the whole time. 
[title] Close your teeth and line them up. [step] Line up your teeth so that the bottom row rests just below the top row, touching them lightly.