I start with general questions like:

- What is the usecase? Is it something that's actually going to be used in the real world?

- Even if the usecase is good, is the coin/token something that will be valuable for an investor like me to own?

- What kind of competition do they have? How does their valuation compare to their competition? Overvalued? Undervalued?

- Is the team good? Do they have experience with blockchain? Do they ave people with experience with their specific market?

- Do they have a working product? If they don't have one yet, do they at least have anything to show besides a whitepaper?

These questions are a good place to start IMO.