Would you recommend I power the Arduino independently of the motor (not via the VIn)?
That is usually best.
Your present setup seems to work, but if the motor draws more current than the power supply can provide, the Arduino will reset.
Motors draw what is called the "stall current" every time they start up, as well as when very heavily loaded or stalled. As already pointed out by OldSteve, this can be 5 - 10x the running current.