planning well and considering factors such as choosing the right light source would be important as this would be your main source of energy for the corals. the right setup/equipment, appropriate live stock and maintenance schedule
very cool, not an expert but most marine crabs have tiny planktonic larval stage that makes it difficult to raise in captivity. one area u might wanna look into is feeding them the right sized live food at the different stages.
u should plan your tank mates in advance cos nano fish usually get bullied if placed with wrong tank mates also get a hardy species that would feed easily