There are is one thing that many experienced basketball officials picking up volleyball have difficulty doing...
Slow down!!! In basketball the whistle and raised arm/fist are simultaneous, the signal for violation is often demonstrative.
In
VB, it's slow and deliberate. Not demonstrative. Whistle,
pause, award point signal,
pause, violation signal.
Most basketball-to-volleyball officials start by doing the whistle and point signal simultaneously, followed immediately by the violation signal.
Slow down. Relax. In volleyball, you have a brief moment to quickly review what you just saw. Take advantage of it.
Come in humble and ask questions. You'll be fine.