I have only been in the position a few of times and it was someone that was completely new to shooting or only long guns and wanted to get a hand gun. After basic safety and handling I have them to my house range or a public range with an assortment of .22 hand guns from revolvers to semis and let them shoot for awhile giving pointers as needed. If I take anything bigger I only let them shoot above .22 after they have shown some competence. If they can afford it I recommend buying a .22, either revolver or semi depending on what they like after a range day or so and shoot that for awhile before getting a larger caliber. If they can't afford an extra gun I let them shoot with me as often as they want using my .22s. Either way only after they are comfortable and show an interest in moving to something larger that I get an assortment of larger caliber for them to try and after they have shown a general interest try to recommend what they buy. 3 people I used this approach on stoped at a Ruger SR-22, one went on to a 9mm Ruger after shooting his SR-22 most of a Summer. I was able to borrow the Ruger 9mm from a friend for him and his wife to compare to my Glock and they preferred the Ruger, the extra weight made it a little less snappy for the wife. She ended up being slower but a better shot than her husband with the 9mm and he was better with the .22.
I forgot I did help one fellow going from airguns to long guns and I used a similar method.
I guess I use this approach because when I was ready to move up form .22 handguns, that is what was done for me to see what I might like best. I didn't need the basics since I had been shooting since I was a kid and learned all that before, plus a couple of NRA handgun courses.