Question:
What should I know before I fly a (stock or FC40) DJI Phantom for the first time?

Answer:
This depends on whether you have any R/C or other piloting experience.

If you have none, it would be prudent to obtain a couple "toy grade" models ($30 or so) and get a couple hours of stick time so you'll be very confident on the controls - especially if you have to switch to manual control (ATTI).

READ AND UNDERSTAND THE MANUAL(S) - Note - it may help to also read the Phantom 2 (bare) manual, as it is much more complete...some parts, obviously, will not apply...

Other than that, these are some basics:

1. As stated in the manual, calibrate the compass (OUTDOORS!) before attempting any flight. Do not constantly calibrate it - once it is set it should be fine unless the Phantom throws off errors.
2. Turn things on in the order stated - that is, the receiver first before you connect the battery. Turn them off in the reverse fashion - disconnect battery FIRST then turn remote (TX) off.
3. Fly in an open area and make sure you have all GPS signals (quick flashing greens) before taking off.
4. Make certain both select switches are UP - that's GPS mode and standard flying.
5. Check prop nuts (older units only)  - if you have the newer props with built-in hubs, you are probably OK.
6. Use prop guards - the Phantom does not take off and land perfectly - it's quite normal for it to lean over in both cases, and without prop guards you may ruin a prop, etc.
7. Use a audio alarm connected to the battery balance - or else use a phone timer or similar to time the flight - if your DJI is fairly light (stock), you should start thinking about landing after 7-8 minutes of flight. If you have additional weight on it, it will be sooner.
8. Be prudent with your first few flights - understand flight times, the effects of wind, etc without letting it get too far.
9. Do not depend on or deploy RTH (Return to Home) unless there are no other options. Do not test the RTH function!
10. Understand NAZA-mode and activate it when you have a chance - test the Home Lock function and use it to retrieve your Phantom when you lose orientation.

Those are SOME of the basics.

For more, check out this article..

My thought is b4 you buy any PHANTOM series buy a small quad and practice practice practice. HAPPY FLYING

Start with an Hubsan X4, it's quite difficult to fly, but a great piece of equipment.

Why can't the RTH be used? How will I know it will work if I need it?