You run a very real risk of destroying your LED by wiring it in series with the motor (and many other loads). The current through an LED must be maintained in its "Safe Operating Area"; this is typically done through a series resistor.
So yes - "best practice" (and the only good practice) is to wire it in parallel, and to use a resistor ...
I don't know what best practice would be.
There are at least two reasons to be wary of having in series LEDs.
The LED needs to be current limited to prevent burn-out.
The LED will drop some voltage (0.7 volts say). That might make the difference between the GPIO level being seen as high or low (i.e. you might not be able to set the output high).