In my experience, you need to be in exactly the right spot, wherever you go. Mullet are odd creatures, and fixate on features such as sewage outfalls or jetties in the same way that some coarse fish do.
You could spend days without ever being near a mullet if you choose badly. Thankfully, where they occur, they usually show themselves in the shallows. Sometimes they are uncatchable where you actually see them, but in deepish water nearby (six feet or more) they can be tempted to feed with mashed bread, etc.
Pound for pound, mullet are the hardest fighting sea fish I've ever caught. and just fascinating