Good post Codger, and a few things I'll add, as if I could call anything a 'career' in Elite, for me it's been passenger missions, running what I've dubbed my Interstellar Transportation Company. Orca, you know.
Good advice about ignoring passenger requests. I'd nudge it further and say don't even open the message, just ignore it entirely. As Codger noted, they won't care if you don't fulfill it, unless they know you know. Don't know.
It's vital, as he also said, to read the fine print. Be sure to know which missions are for criminals and wanted passengers. Take them at your own risk, but I'd advise skipping them entirely until you've built a smuggler ship. My Orca was built for this and idles at a very low temp, making it ideal for these. But if you cannot avoid scans through ship builds and ship handling you don't want to be doing these.
I'd divide the passenger missions in to more types
-- Bulk Hauling -- These are the ones which will say something like transport 54 businessmen. These missions allow bleed over multiple cabins and are one-way, short hop usually.
-- VIP transport -- Exactly like bulk haul, but require their own cabin
-- Smuggling -- Criminal and wanted transport. Work as above, but carry additional peril.
-- Sightseeing -- These are round-trip missions to tourist beacons and the like. Unlike the mission types listed above, which boost trade rank, sightseeing missions boost exploration rank. They work like VIP missions and require their own cabins, no sharing between stacked missions like bulk haul missions. I really like these, and it's what I cut my teeth on in my early days. They take you to some of the most striking places in Elite, and have the collateral benefit of often taking you to systems with valuable planets to scan. Lots of ELWs and WWs for example to boost the profits from the expedition.
There's one pitfall from sightseeing missions that prospective bus drivers should be aware of. Arrival distance is NOT shown in the mission description, and it's pot luck. You will have no idea of how long the supercruise is to the tourist destination. If could be 100 ls or 400,000 ls. I like this sort of unpredictability, but I also know there are commanders who would not care to fly these for this reason.
-- Long-range sightseeing -- These are the ones that go for many thousands of light years, usually taking a 'famous explorer' to his or her destination and back. You'd think being famous for this they'd already have a ship, but perhaps fame softens them and they think they are above such mundane acts as piloting.
I use two ships for this mainly. The Orca, which now is my sightseer and smuggler
A ship builder, outfitting and comparison tool for Elite Dangerous
coriolis.io
Very fast, with good jump and idles at 14% heat. Cabin arrangement is modular. I have a wide variety and mount them before stepping in to the passenger lounge with a mix of first class and business class to open more of the missions on the board. After selecting I then remove the unused cabins to maximize jump.
And a Krait II Rumble Bus
A ship builder, outfitting and comparison tool for Elite Dangerous
coriolis.io
This is used for bulk haul and one-way VIP missions. Seats 55 business class as shown. It's armed to take on interdictors, and the passengers seem to love the action haha