Primary focus on "development", not "winning" - subtle difference but very important.  Winning is desirable of course, but making it your primary focus, especially your primary short-term focus, will most likely lead to bad decisions in your training program and game execution (see "don't teach anything you have to undo later" below).

Maximum touches on the ball during training sessions - make sure your practice plan leads to as many touches on the ball as possible.  This can be accomplished by separating the players into smaller groups during drills or by designing your practice to include drills and games that force many touches on the ball.  This is the primary reason NTX has moved to the small-sided game format.

Don't teach anything you have to undo later - for instance, many coaches of the younger players put their players in a defensive "wall" on the opponents kickoff - an alignment that will never be formed when they grow older (maybe in futsal).  Instead, teach them to spread out on the kickoff and cover the critical defensive areas.  Otherwise, at some point down the line you'll have to teach them to cover the space, hence undoing what you taught them earlier.  Another example would be a coach of the younger players putting a single player in front of the opponents goal with instructions to "wait for the ball" - and leaving the player in that position during the entire game.  On down the line you'll have to undo this practice and teach that player how to stay "onside" and how to "make runs to the goal", hence undoing what you previously instructed.