Having been on both sides of the angel equation, I have a basic inquiry I prefer use:
1) Find out why the person invests and what type of deal they like
2) If the deal fits, do they have money to spend in the time needed
3) If they do, is this someone I'd like to work with
4) If yes let's talk more about the deal and discover whether there is a there there
Experience has taught that there are basically 4 types of investors:
1) Someone that likes the person or the team - You can sell IoT or pet rocks and have them go with it
2) Someone that likes the concept/space/market/approach - They like scratching a particular itch and as long as you're schatching they're is potential
3) Someone that likes to maximize ROI - The best can make you rich, the worst would sell both you and their mother into slavery
4) The last have no idea what they're doing and "heard they should invest" (Which unless you know well them and they're married to your brother/sister is usually not worth the effort)
No-one is just one but folks have preference. Discovering that isn't that hard if you ask the right questions and recognize which questions are most important to them. Do we know any of the same people? Do the same things? Can we go deep on how the gadget or product works/who it serves? Are we looking at market size, margins and increasing value of the organization?
And don't be shy about asking if they're planning on investing in the next six months. People that are in angel networks often have investing groups with an investment cadence. If they him and haw and wax non-committal it is again time to step. Smart angels have already assessed the amount they're going to put in play within reason and have a strong ability to say yes to something they like.
On the other hand, if you just love chatting it up with folks who might have money... you'll have an endless supply of GANDs (Great Advice, No Dinero).