Miracle of miracles! You have persuaded some players to perform or record your music. That suggests that your relationship with them at least begins on a co-operative footing. But when it comes to rehearsals, how much should you be in charge? Should you let them work at it themselves and get the best out of the dots you have put in front of them? Or should you intervene to get the piece exactly how you envisaged it? There are arguments both ways.
Those players will be used to encountering music they haven’t seen before, often by a long-dead composer, who they know will not interfere. They will approach that music on its merits, and find the emotions and meaning of the piece as best they can, using their experience as musicians. So why wouldn’t they do the same with your piece?
On the other hand, they may somehow miss your point, get the wrong end of the stick, or see something in it that you hadn’t intended. Or not pick up that a particular detail is crucial.
Of course it behoves you to put as much helpful instruction in your score as you reasonably can. If a score is undermarked, then a rendition is likely to depart from what you had imagined, or at least more time will be taken in rehearsal. But if you specify markings too profusely they will become a stranglehold, or else be ignored. Scores by Haydn and Mozart and their predecessors and contemporaries are generally sparsely marked, and the parts were probably written out in haste. But those composers were generally directly in charge of the performance and so could instruct the players there and then. They didn’t expect to have performances 200 years later.
I think the best strategy is to provide your sheet music as early as possible, so that the individual players can try them out and ask questions before their first rehearsal. If you like you could tell them some background to the piece, or what you think it is about. Then let them rehearse together on their own. Once they have some familiarity, but before everything is set in stone, then is the time to work with them. Be appreciative of their progress so far – which will be some way towards your intentions. Some adjustments will be required, no doubt. Put those forward as suggestions; “Have you tried ….”, “Can this go a little faster?….”, “Let’s give it everything at that climax …”, “I’d like to hear the flute a bit more prominent ….”. Encouragement should be the watchword, rather than criticism. Take in their feedback and respond. If they say something is impossible or too difficult, then try to find an alternative, a compromise, that lessens the difficulty. I find that performance tempos generally work best a little slower than the computer playback, for example.
A tricky situation is when you are one of the performers. You know your piece far better than the others do. This can be a bit frustrating. Keep your cool: have patience, take things slowly in rehearsal, demonstrate as necessary, make nice remarks when things go well, be prepared to compromise. And applaud them thoroughly at the end.
In summary, treat your performers well. They are doing their best and you need to keep them onside. The end result may not be quite what you expected, but it could exceed your expectations too. Give them every chance.