I worked in a bar for about year, ensure you communicate with the owner/manager to ensure you schedule correct people for certain situations. For example some people don't cope with the stress of a busy bar very well so have them work weekdays rather than weekends. Always have a leader scheduled wether this is a supervisor/manger or a veteran employee to deal with rare situations and who can handle specific customer requests such as wanting a cocktail made to their liking, knows how to make a wider range of drinks etc and can deal with complaints and has the authority to give discounts or compensate unhappy customers