Quote Originally Posted by Medved View Post
Й is like Y as in Yes or Toy
И is like EE as in bee

as for Ш vs Щ you have to go much further into phonetics to learn the difference.
The thing is that your SH as in SHore is neither Ш nor Щ; it's like in between them and you have to learn the correct articulation of the Russian sounds to feel the difference.
Just to clarify, the main difference between И and Й is that Й is held shorter than И, right? It is a little confusing, but I guess practice makes perfect.