Don't overheat the pan! If the fish sticks too much, or doesn't come free easily after ~1 minute, or burns, your heat is too high. This varies by pan type (non-stick is more forgiving, stainless less so)
Don't fiddle with the fillets as they cook! Just lay them in and leave them alone. They stick at first, so moving them will tear them.
Cook skin side down first, this is more forgiving.
Don't use frozen fish for this!
If the albumin (white stuff) oozes out, you overcooked the fish a bit (or maybe a lot)
