How successful a show is going to be, starts at the audition. A general comment to all directors chose well.
Can the actors auditioning do what is required? Present humour, act dark drama, sing, dance, speak clearly with a specific accent, whatever is demanded by the script, chose well.
If you cannot find actors with the age, appearance and talent you require, then perhaps change the choice of play.
Never cast ‘old friends’ just to solely give them a chance and to fill cast places.