Different procedures are used in real world operations. The following explanations are therefore only exemplary.
Easy Operation Mode
Realistic Operation Mode
The realistic mode requires a certain understanding of the Rotax engine and appropriate training. Otherwise, the engines can not be started and will be damaged in the worst case. Please read the Section 3 - Normal Procedures carefully. Summary: You need to rotate each prop until you hear the bubbling noise from the oil resevoir twice.
The lower the fuel pressure, the lower the chance of a successful engine start.
If you shut down the engine and turn off the fuel pump there is a high chance of a good restart without fuel pump because there is still enough pressure available. Pressure will drop quickly though.
The lower the engine temperature, the lower the chance of a successful engine start.
If you load the flight at a cold day, you will need more prop rotations for the oil distribution. Additionally, the engine will start quicker, if it's still warm from a previous operation. The engine temperature will drop depending on the outside temperature difference.
Using the choke to pump in additional fuel is recommended when starting from cold & dark. If you restart the engine it might not be necessary because the fuel pressure is still high enough.
Usually no throttle input is required. If the engine doesn't start up properly, you can try to add some power though.
Even under optimal conditions, the engine does not always start at the first attempt. You should not hold the starter for longer than 5 seconds to save the battery.