Pussycat mode...
In Input - Stabilization Modes, set Attitude, Attitude, AxisLock, Manual. This mode has self leveling and is easiest to learn with.
In Vehicle - Throttle curve set the 5 dots to 0, 40%, 50%, 60%, 7%. There is only a limited range of useful RPM range to learn now to fly. The far right dot limits the maximum speed of the motors. As you become more comfortable you can steepen the curve to gain higher speed.
In Stabilization - Responsiveness. Slide Attitude down to about 25. That limits the maximum angle the vehicle can pitch or roll, which limits maximum speed.
About launching...
After you arm, don't start the motors and let the vehicle sit there with the props spinning. That can cause 'confusion' in the FC which can cause severe instability or the aircraft even flipping over sitting on the ground. The correct technique is to barely touch the throttle to make sure all the props are spinning, then immediately punching the throttle to about 60% to get the vehicle off the ground, then almost immediately down to 50% to maintain a hover about shoulder high. The purpose of that is to get the vehicle out of the prop wash smashing into the ground and bouncing back up to the props which can cause weirdness. A smaller multi can fly comfortably stable about knee high but you have a much larger 500 which throws a LOT more air.
About flying...
For first flights DON'T touch the YAW except for minor adjustments!! The vehicle should ALWAYS bepointed with the nose AWAY from you. I know you have experience with fixed wings. The difference between fixed and rotary wings is that the rotaries have this weird ability to stop in midair and even fly backwards.
That will be EXTREMELY disturbing to you till you get used to it because you're -used- to always maintaining forward flight. With the nose always pointed away pushing the elevator forward will mode the vehicle away from you and pulling it back will bring it towards you. The DIFFICULTY/CONFUSION arises when the nose is pointed towards you, you pull back in the elevator, and the vehicle travels away from you. That's where your fixed wing experience causes yor brain to have a meltdown.
Learn how to move the vehicle towards and away from you, and left/right with the roll stick. DON'T jump quickly into doing any circles or fig-8s or whatever or as described in the previous paragraph you WILL crash quickly.
There are other exercises to learn about multi orientation and then get into more advanced motions for the first time.
A 500 is a pretty big beast. The 25-deg max pitch and roll I mentioned takes a bit of space to -stop- a maneuver. I would recommend flying that thing in about 100' worth of space, where you are another 30' outside that space. It takes distance to start a maneuver, and then to stop it. When it's coming towards you you don't want to let it get too close to you because it -can- cover many yards of distance in only a couple of seconds, which without the experience you don't have the reactions for yet to prevent 'bad things' from happening.
If (read: WHEN) you lose orientation you need to STOP and regroup your brain. When you find yourself in a moment of indecision set the right stick to neutral and lower the throttle to about 25% to allow the thing to land. Then think about what happened and start over again. It is like a fixed wing in the sense that once it's traveling it -will- keep going until you tell it to do something different. However while you do have the fixed wing muscle memory and reactions this multirotor stuff requires -different- reactions.