The trick to smooth orbits is to turn on the center cross hairs in the display. Yes obviously they also take a lot of practice, but without the cross hairs enabled it is hard to tell if you are losing your orbit center until you are so far off that a correction will show in the footage. Every drone flies differently and orbits are one of my favorite maneuvers, so when I first get a new drone I take it to a park, turn on the center cross hairs and orbit at full speed in Ludicrous mode around a tree clockwise and counter clockwise until the battery dies. I then repeat it and go the other way. This helps me gain muscle memory on how that particular drone accepts stick input during an orbit.
Another trick while you are learning is to shoot at 60FPS. When you are starting out, you only need a few good seconds out of an orbit before you jump cut to a different shot; at 60FPS if you only got 2 perfect seconds out of your orbit but the next cue point on the audio track is 3 seconds away, you can drop the playback speed for that clip to 50% to reach 4 seconds. Last but not least don't show the beginning of the orbit. I hit record before the start of the orbit then typically do a full clockwise and counter clockwise 360. While editing I pick the best part of the orbit that does not show the start or end.
Personally I always keep the center cross hairs on, they are a great help and will alert you to problems early enough that you can fix it (or start over) before it shows in the footage. For example if I am dollying in on a car but there is a cross wind the cross hairs will tell me immediately if the drone is drifting off course.
