Hi,
Sharing a few common functions that were the most useful for me:
- Pivot tables
- Lookups: Index Match, Index Match Match, V/H Lookup, or X lookup (in the newer versions of excel)
- Sums: Sumproduct, Sumif
- Goalseek
- Conditional formatting
In addition - do note that formatting and etiquette are equally as important (e.g. don't combine hardcoded numbers with formulas).
Lastly - you will never be able to prepare for all the unknowns and problems that you face while doing excel on the job. But really all you need is google and colleagues who are willing to help you → this will get you to the function/solution that you need 90% of the time.
All the best!