Ah … the Flightseeing grind in Career mode… it can seem that the only real objective here is to amass credits and XP on your way to bigger and greater things, but IMHO here are some things players new to Career Mode should think about to make better use of this time… by treating it as a learning opportunity.
Doing this will get you A/S ratings on your flights, and really help you get those credits fast …
PREFLIGHT/MISSION SELECTION
#1 To avoid frustration, pick FlightSeeing missions at PAVED airports (in the USA, these airports will have a 4 letter identifier beginning with K—. This will steer you clear of bush strips you might not be able to take off from , with the aircraft supplied in the beginning stages.
#2. Make sure your mission buttons/keys are properly mapped (either in 2020 mode or 2024 mode) so that you can click on the mission steps (Get in, start engine, talk to ATC/Acknowledge etc.)
#3 Be prepared to take it slow and easy…
MISSION FLYING
For Flightseeing objectives, the Sim focuses on flight smoothness, and being able to take turns at low speed while maintaining a fixed altitude. Here is where the learning opportunity exists.
a. Get to know your aircraft (172, Aero, or Corvalis) pitch, power, and speed settings.
How much Power for Takeoff? Flaps or no Flaps? Rotation speed, cleanup speed, and best climb speed. Learning these, will help you make smooth, repeatable takeoffs every time.
Wind – wind will vary across missions (sometimes too much but thats ok) Learning to correct for wind on takeoff and enroute phases is a skill you should begin to develop!
b. En route flight - You can follow the route indicated by the GPS and the Blue Boxes - Here focus on trimming the plane to maintain your desired speed, and altitude. Again, try to come up with specific numbers for power (RPM), pitch (degrees above horizon) to get a feel for how the simulated aircraft behaves. This will help you converge on settings that make the enroute travel easier.
c. Flightseeing itself. Typically the Sim will specify a low speed (82 knots) and a specific altitude and turn radius to maintain.
I have found that flying 10 knots SLOWER, with a notch of flaps out, allows for a much more controlled and smooth flight around the area.
About 1-1.5 NM ahead of your Flight seeing waypoint, you may need to cut your throttle to idle, and plan a descent to the flight seeing height. Again good practice for controlled descents.
Flying Chandelles (Figure 8s) is something commercial pilots need to do to pass their checkride, so treat the flight seeing phase as that! Again, pitch, power and flap settings are key to a v smooth, slow and enjoyable flightseeing experience for your passengers!
d. Then all you have to do is transition back to the enroute phase, and then prepare for landing.
Here, figuring out descent rates, and keeping a smooth, stabilized descent all the way down to the runway should be your goal. Again, be aware of, and correct for wind.
Aim to cross the runway with about 5-10 knots above your stall speed (and you will get a good idea of how that varies with various wind conditions and flap settings, also — experiment with when NOT to use flaps, when to use full flaps for a slow and controlled descent to the runway and landing!_)
Being aware of these things, and getting to know the planes behaviour in the Sim, and learning to adapt and change with conditions will greatly enhance your enjoyment in this phase.
e. Get familiar with the autopilot. That can help in the enroute phases, as well as your approach and landing phases. AFAIK, there is no penalty for using automation in the activity, obviously, you will have to transition to manual flying for landing. But even in FlightSeeing mode, having the AP maintain your altitude while you control power and bank is a valuable effort saver, and is NOT cheating 
!! Pilots should learn to leverage ALL RESOURCES available to them for safety and workload reduction!!!
If you focus on developing these skills, you will become a better Sim pilot overall, and have a playbook for learning newer and more complex aircraft, as well as enjoy the Flightseeing activity much more!
The Sim (post Update 1) has much improved, and I can honestly attest, that I am having a great deal of fun taking my sim-flying activities seriously as a learning experience — as well as enjoying the variety that comes with the sim.
And speaking of variety, earning credits and unlocking certifications (Turbo prop, Jet, Commercial etc.) instead of saving to buy an aircraft will give you a wider variety of missions to choose from for the next set of credits… so you are not limited to just FlightSeeing ones…
Lastly, you can pick missions from anyhere in the world, and definitely look for more lucrative missions — for e.g. in FlightSeeing 2000 Cr missions instead of the 950 / 1000 ones typically spawned near your home airport. Those missions have multiple flightseeing sectors on a single flight and pay more! – When picking them, don’t pay too much attention to the forecasted time to complete, (eg. 1 hr 30 missions) usually take much much less than that to complete once you know what you are doing
Happy Simming!