Tactical rifle fourth huh... I think you should be issued an M4 at birth but that is just my opinion. I'd feel naked without mine.
I think a good little .22 rifle and/or pistol is paramount for practice and fun. Everyone enjoys it and it is good for focusing on fundamentals cheaply.
For the first "real" one, or first handgun, they should get what they can handle... A simple striker fired pistol or DA/SA revolver would be my recommendation for a handgun. I like the Glock because it doesn't get much simpler, but I'm not a fan of their new stuff.
For a shotgun, a cheap Mossberg pump if they have to ask. If they don't have to ask, well, the world's an oyster.
As to which they should get first, I'd argue the .22. No point in getting a 9mm for the first one and firing one box then putting it up. Dip your toes with the .22. It isn't ideal for defense, but they made it this far, right? And why should they skip over the most important part of firearms training --safety, practice, the fundamentals? My first rifle was a .22 and my first shotgun a single shot 20ga. Why? Because I was a kid? No. Because I was new to firearms and this is the best way to get introduced.
They can use the .22 for defense until they master that. If they don't or can't master that, perhaps they should consider not using firearms. They can be very dangerous in the hands of the ignorant, and every new shooter should be considered ignorant by nature until sufficent practice has taken place to familiarize the shooter to the fundamentals of marksmanship and safety.
THAT should be your first and foremost concern as an instructor, and should influence every decision and recommendation you make. *I* think. Some "instructors" I guess recommend you pack a .500S&W and even carries one to prove it --this is very bad advice and a poor example to new shooters and does them a disservice.