One of the biggest early obsticles in RC flying is training your brain to know which way to push the stick when your plane is in various positions relative to you. E.g., "My plane is coming back at me. I want it to go to my left, which way do I pull the stick?" Obviously easy to figure out given a few seconds, but often you don't have a few seconds to figure it out. You have to train your brain to intuit it.
RealFlight is the 500lb gorilla in the RC flight sim space, and a good piece of software. But they also have a history of expensive and frequent upgrades, and charging for new models. I prefer Phoenix, which so far only has free (and frequent) updates, includes models from my favorite RC manufacturers and lets you download new models for free. Absolute RC is the only current RC flight sim that runs in OSX, but I still prefer Phoenix in Parallels or Bootcamp.
You're going to spend $100-$200 on a simulator and controller, but it's well worth it for being able to practice in a pretty realistic setting before you start flying real planes.
Alas, the big boys are Windows-only software :-(
There is at least one inexpensive RC simulator out there that runs on Android (and has pretty good glider simulation), which lets you use a PC USB controller for the sticks. You need a USB "On The Go" (OTG) adapter cable to plug the full size "PC end" of the controller into the micro USB socket.
I had a free simulator that worked on Mac, but I forgot its name after it stopped working.
Both Phoenix and RealFlight come in packages either with a controller, or a cable to plug in your RC controller.
transmitter vs controller images:
I like Phoenix better for heli. Once I got past the basics it felt like Real Flight had just enough control latency to make it more difficult. The context for this is comparing actually flying the real heli against training on the sim.
Because of the approach I took I had exactly zero crashes with the TRex 500. Which is good 'cause I have somewhere between $1,500 to $2,000 into it with all the upgrades.
Today, when I teach someone to fly, I follow a progression on a sim from a pure glider to various powered planes. It works like a charm.
I've been thinking of putting together a little course to help get people get started. It can be really frustrating if you don't know how to start and what the progression of exercises should be.
Not affiliated, but a big fan:
I took at test to be a Navy Pilot a long time ago that had what they called spatial aperception which tested exactly that. It had the picture of a cockpit, then four different pictures of planes in various orientations and you had to choose the correct orientation based on the cockipit. I'm 100% sure I did well on that part because of playing flight and FPS as a younger man.