Is there a heuristic as to what should be at sorting layer 0? Should that be the layer of origin for the player? I'm sure it doesn't matter but I like standards :)
Ideally you'd have layer groups for specific objects. Like a props layer, a player layer, etc. Then you'd use the layer order within those groups so you're not using one layer that has the top object with a value of 10 or something. Doesn't matter much but it makes it easier to order things.