Your group will be your best resource for the specifics. I’m not SAR but I have worked alongside some guys a few times and had some informal classes on it.
But some general things to do or consider.
Learn to navigate comfortably in all conditions.
Get familiar with SARTopo/CALTopo. Especially Range rings, and free from shapes, sharing maps via QR code, PDF etc, and creating and sharing tracks. This is essential on the planning/management side and may be one of the biggest factors in success I’ve seen in some our local searches.
Download the lost person behavior app. This will help you narrow down how large of a search area to start with based on the persons age, mental status, injuries, etc. Remember they may not be thinking logically. Something went wrong in order for you to be called out. So don’t make any assumptions about how they “should” have followed a terrain feature or stayed on better terrain or whatever.
Be in great physical shape and comfortable in the woods or mountains you will be living near. SAR personnel get lost occasionally while on a search and you want to ensure you are an asset and not an additional liability.