I thought I would do a vain attempt of summing up my experiences from building and setting up 5 AQ frames so far. Its probably a little fragmented, but please bear with me...
First of all, dont get discouraged if you dont succeed at first. It took me 3 months to get the first to fly, but from then on it gets easier, and the tools have become much easier to use since we started.
Start out with 6.5, its very simple to upgrade to 6.6 once you have the calibration done. 6.6 is still "experimental"
I recommend starting out with a simple frame, 50 cm quad with 10" props is a good starting point and it will fly good on the default PID´s. Once you have the static procedure completed you can move the board to a new frame and repeat the "dancing" part without too much hassle.
Always keep the uSD card inserted when flying, not only will it provide vital clues on your tuning, but we cant help solve problems or bugs if you cant provide us with a logfile of the incident.
Pay attention to wiring of the frame, braid/twist all wires and avoid loops and hoops. In general, try to keep the power distribution away from the main board.
The GPS antenna wire can be ripped out of the plug if you dont take care when removing the antenna. I have like 4-5 antennas lying around without IPEX plugs anymore to prove that point. Just keep a decent pair of mechanic tweezers in your toolbox and you will be fine.
If using reflashed OEM ESC´s, calibrate throttle often! Autoquad need well balanced ESC´s with high motor refresh rate. ESC32 is recommended, but a F30 or similar with a SimonK FW will work well too. Atmel-based ESC´s with internal oscillators are NOT recommended!
I have always mounted the boards on plastic standoffs without any form of vibration dampening. Using rubber standoffs did not work for me, and is not recommended. Balance props (and motors if you can).
Get some form of wireless telemetry setup (Bluetooth, Xbee or similar), and use an android phone or a small laptop to confirm that you have a steady HUD before taking off the first time. Its also a vital tool to change PID settings with.
Pay attention to your mixers and IMU rotation parameters. The default in the release code is 45 degrees IMU rotation, denominated by the diagonal arrow in the front right corner of the board. You will be able to take off with a wrong IMU rotation, and fly (sortoff), but it will come down again when stabilisation overcompensates at a 45 degree angle. This recently cost me a broken boom and two CF rotors on the 950 hexa - simply because I forgot to check IMU rotation and just took off after a FW flash.
Keep backups of your files! Especially the params-file from the calibration process, but I also keep the files from the calibration process.
In my last calibration of a board for a medium sized hexa, I had to use the ziplock bag method to avoid condensation. It worked extremely well, so I am gonna do that from now on and I recommend you do the same.
For tuning the attitude PID, you mainly need to tune rate and angle D. In smaller frames (8" props) you usually have to lover rate and angle D by up to 50 percent, while larger frames/props will need slightly higher rate/angle D to fly well. But again, start out with a "normal" frame and in most cases the default PID will work well, provided your IMU is properly calibrated.
If you want to test the newest featues and have complete control of your setup, I recommend getting the personal license for Crossworks. I dont code as such, but more than once it has been handy to be able to change something in the source and recompile.
Thats what I can think of right now...