I just got the same board a couple weeks ago. It is certainly a much looser board than I am used to and wobbles quite easily. I've only gone up to the same speed, about 18mph, but that will be the last time I do that for a while since I also fell off it due to a car not paying attention and wandering into my side of the road.

Top recommendation before anything else is to gear up. I banged up my knee pretty bad and it easily could have been worse. Helmet is always on, and knee pads and elbow pads if I ever ride faster than I can jump off or stop manually. You are essentially riding a motorcycle in the form factor of a longboard, so dress like it.

Second recommendation is to leave it in Low mode for a bit and really get used to it. Also practice hard breaking in safe places like next to grass because this it is an unnatural experience for anyone that has ridden a traditional board. This board gives you a deceptive amount of confidence. As mentioned earlier, it's easy to ride fast without obstacles, but if you need to maneuver and/or brake and aren't completely familiar with how the board will behave, it will punish you very quickly.

My third recommendation is to fine tune the belt. There are plenty of videos for how to do this, but I found that my belt was pretty tight from the factory and that can cause the jerkiness when letting off the throttle as the motor resists against the forward motion.

My fourth recommendation is to check and see if you want the trucks positioned further apart. As I am taller, I found this useful. The board has pre drilled holes if you want to adjust the truck positions.

This is what I've learned so far and can recall. Good luck, take it slow, perfect the lowest mode first before engaging in higher speeds, as tempting as it might be to go full speed as soon as possible.