If you do the BA training on UiPath Academy there’s a spreadsheet with a questionnaire. I have added to that for what’s important to the organisations I work with. Start with that though.
I always record the process, taking this saying from the military “don’t expect, inspect”
People will tell you things incorrectly, either because they want their automation to be prioritised higher, or by mistake. You need to check everything yourself. Do the process yourself manually to make sure it is what they say it is. Check through hundreds of instances of the process to find anomalies that nobody told you about.
It’s usually more complicated than people let on - there’s a long long tail of variations in edge cases of business processes. You need to be able to draw a box around the high-value, lower-effort part and say “this is what we automate, the rest can be done manually”. Otherwise you’ll take much longer to release something that only provides a little bit more value.
If you design and build things properly and in an Agile way, you can do it iteratively so that later releases have those extra enhancements (if it makes sense to do so).