L and R - is it Light or Right?
Minimal Pairs - lake-rake, ...
Pronunciation - Minimal Pairs R/L 1
Pronunciation - Minimal Pairs R/L 2 
Pronunciation - Minimal Pairs R/L 3
Pronunciation - Minimal Pairs R/L 4

Try listening to L and R alone

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Watch a video showing the two ways to say R
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Minimal Pairs -CL/CR, FL/CL

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Watch an animation showing how we say R
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A video about how to pronounce R


Minimal pairs for other sounds:
American English Pronunciation Practice (For ESL/EFL)