There are many factors that go into a GPS loss / flyaway. Run all of your updates, take it easy at first, fly in large open fields, stay away from metal (including reinforced concrete), buildings, tall trees, cliffs, and cell/radio towers. There is a GPS module in the drone and controller so what applies to the drone, applies to you.
Flying while looking at the screen is fine, but you need to be able to fly the drone comfortably and instinctively from any orientation while looking at it. Left is right and right is left when the drone is facing you.
Manually land the drone. You can bring it in much softer than the auto landing.
Be prepared to hit the (X) cancel button on the screen if the drone goes into auto landing.
Don't fly the battery down to less than 8-10 minutes remaining unless you're bringing it in for landing or have it close. Again, be prepared to cancel the auto landing if need be and know your return altitude.
Wait a couple minutes after getting the, "Ready to fly" command to let the drone lock onto a few more satellites before taking off.
Although it shouldn't happen, hitting record before you take off will help prevent EMI. Mostly it's just a good idea so you don't forget. I've flown my drone before and thought I had captured some great moments only to realize I got so caught up in the moment I forgot to hit record. Not a good feeling.
Get a couple apps for your phone. Magnetology and UAV forecast are good. If the kp index is 4+ your chances of communication loss/error are much higher. Fly with clear skies and low kp and you should be fine.
For making videos, try to use Karma as intended. Be sure to use the Grip and get some hand held/body mounted shots. The drone is meant to supplement these shots and will make your videos better and much more enjoyable to watch.
Go to GoPro Official Website - Capture + share your world - Karma
and learn as much as you can by watching videos and reading the FAQs.
Finally, make sure you use a recommended SD card. https://gopro.com/help/articles/Block/microSD-Card-Considerations
I purchased Karma when it first came out and again after the recall. I've lost GPS once and the drone behaved as expected. If you do the simulator and follow the above advice and what others have posted, you should be fine. This isn't advice that is solely for Karma, but all drones. You want to have at least 12-20 flights before you start pushing the limits of the drone, and even then, know your limitations as well as the drone.
Happy flying and congratulations!