Synth flute and sax played on a keyboard (controller) obviously will not sound "real" to flute and sax players... but these easy hints help you get closer.
1. Remember that wind instrument players have to breathe!
Deliberately add breaks, even if they're short. Think of where *you* would have to breathe if you were actually playing the instrument. Logical places for songs with words are at the ends of sentences or phrases.
2. Don't accidentally create di-tones or chords.
That is, go into the "Piano Roll" (notation) section and ensure that the MIDI notes barely touch into each other. You don't want 2 or 3 MIDI notes in the same space for wind synth instruments. In fact, staccato (very short MIDI notes) such as for flute especially gives a playful or joyful sound. (Actual violins are played with one note blending more into the other, so the MIDI notes can overlap a little... not too much.)
If you look at the MIDI notes and see overlap,
you can often do a better edit shortening those notes if your first go to CONTROL (in GarageBand) and turn OFF "Snap to Grid". That enables you to have quarter notes that smoothly extend a bit into the next quarter notes but without the di-tone of 2 full notes being played simultaneously.
3. If there's a "muddy" sound or the meter is running 'hot,'
even after you shortened the note lengths, check (in GB) the "brighteness" of the green MIDI note to see if you accidentally played some notes louder than others. If so, select those notes, go to Velocity, and lower the volume number.
4. "Quantize" notes easily (so they hit on the metronome count):
a. In the SCORE section, highlight one note, go to Edit > Select All.
b. Go to Align To (under the Piano Roll button) and select 1/8 Note.
That gives a quick quantizing.
c. Then in the SCORE section, highlight all actual 1/4 notes PLUS the first note of a pair of 1/8th notes. Go to Align To and select 1/4 note.
d. Check the MIDI section... for faster music, some of the notes will be one above the other after quantizing. Turn ON "Snap To Grid" and then slide the 2nd note over to be in its place.
Much Joy to you experimenting with "playing" wind instruments more realistically!
©2018, 2011 DianaDee Osborne
An updated version published 17 April 2018.