Yeah, PC flying is a little less more expensive than real life... Okay, maybe a lot more, but it's still damn expensive. However, some of the addons you may find out there give the exact same simulation that full motion simulators do, just without the motion. In fact, there is a school in Florida for flight training that merged with Delta sometime in the 2000's that use PC's first, and then they move on to full motion.
Anyways, it's good to start out with freeware first and then to see what you're doing.
BEFORE YOU GO ANY FUTHER:
There are a few things you need to know about how FSX and Windows work together. Even though Microsoft made both, they don't quite work well together. Depending on you OS too, things could get bumpy along the way.
If you haven't already, make sure FSX is not installed into program files, or a windows protected area. Instead, just go to your storage, such as C:/ and create a folder named FSX or something, just so it's outside of a program files or windows protected folder.
Second, find the FSX.app or .exe and set it to run as admin always by going into properties>compatibilit>on the bottom. Once you do this, any other application that talks to FSX must be set to run as admin always. Doing this enables more privileges for FSX to take on by itself rather than to ask you 24/7.
Third, if you don't find UAC annoying as is, go ahead and turn it off or to it's lowest setting. Personally I completely disabled it in regedit, but that's up to you. A lot of programs don't run well with it on, including addons for FSX. If you also have a good AV like AVG, go ahead and turn windows defender off, unless it already is.
Fourth, download
this. It is a LARGE_ADDRESS_AWARE flag, that you use to give you more VRAM. If you already know about OOM's then you should've already done so. If not, here's what they are:
Essentially, your computer only has 2, or 3 gigs of ram that it can use per program. After that is used up, you will receive an OOM (out of memory) and close the program. Even though you may have 8, 12, 16 gigs of RAM, VRAM is specifically made per program limits, based on x32 bit programs.
FSX, P3D, and FS9 are all x32 bit programs as they are considered legacy products (not P3d in its age but it's construction). Xplane is the only x64 bit flight simulator out there, so OOM's are very rare for them.
Anyways, if you have a x32 bit operating system, you will only have 2 gigs of VRAM, and x64 gives you 3 gigs. By doing the large address aware patch, you get 3 for x32, and 4 for x64. All you do with the program is find the FSX.exe (you can find this x10 easier by enabling 'show extensions') and select it. Then it's done. After that, delete the program if you want...
I'd recommend strongly before going on much further, to make sure FSX is not in a windows protected folder, or any other application you make in the future. It's going to cause headaches, and I try to minimize those as much as possible. If you have it in program files, then when you uninstall FSX, you need to make sure everything is gone. Make sure you go to Documents/flightsimulatorfiles/ and delete everything in there. Make sure everything from the APPDATA folder pertaining to FSX is gone, and make sure the registry is no longer exisiting. Yes, it's a lot, but FSX was a rushed program, and FSX SE doesn't alleviate all these issues.
Hope you have fun flying and getting the basics down. Do some flights in the Cessna 172 around the TNCM (Saint Maarten) area and land at a few of the airports near you. Once when you feel like you're ready to step up a notch, learn how to read charts for airports and SIDS and STARS. After that, you'll be gold for VATSIM... But that's another lesson.