. The answer to the "How do i do it" question is just do it. Stick to one idea and see how it works. If it doesn't work try another idea.
. The prints should show an appreciable better IQ than a typical tourist can shot with a point and shot or even a bridge camera. Amateurs all over the world are your competition.
. Nice (and quick) portraits may need some basic background and lighting.
. You can have some landscapes and selected spots backgrounds previously shot and offer the print alone or a layered print with the tourists in it. Some pp will be needed.
. In my last travel to China there were a lot of semi pro photographers that had placed stairs or platforms at specials optimal spots. The tourists stand there, click and voilá: a perfect pick at the perfect spot.
. You can offer a quick print. Decide two or three standard sizes. You need a dedicated print for that. Bigger prints can be a mess to deal with. But you can ship bigger prints at better prices.
. Offer framing. Three frame sizes, different designs. If you give the option of framing you will get more money.
. To sell or not to sell the digital files? A dilemma.