I cannot emphasize enough that the conductor's knowledge of the score is the most important factor in his success. This will determine his ability to allocate rehearsal time and determine where the greatest effort should be placed in rehearsal.

Also, whenever possible, check the orchestra parts in advance so that time is not wasted because they contain contrary indications or, worse yet, outright mistakes.

Some musician mistakes in rehearsal are obviously just slips. You should be able to ignore them and trust in the player’s own professionalism. But when you have to respond to mistakes or make any requests of musicians, be specific in your comments. Identify the problem and state what should be done to correct it. Merely repeating a passage over and over frustrates the players and wastes time.