Any off-road tips for a 13 year old?

Go ride and have fun

Go ride your bike, ride with people faster and more skilled than you. Practice on an MX track, that will make you a better woods rider.

You need to learn from a much faster Josh Knight (multi-time ISDE gold medalist, NHHA winner, Idaho City winner...several times, I think)...here is a link to his Youtube channel. He actually has a website with a ton of content you can subscribe to as well (www.ridewiththeknights.com)

https://www.youtube.com/user/TheKNIGHTeDITS

Bike setup will benefit you a lot. Soft is good both in suspension and motor. What type of Offroad? Fast flowy, slow technical?

I always told my kids when they first started to look ahead and not down at their front fender. Reading terrain is a big part of learning how to ride safely/fast off-road

Stand up, look far ahead and look where you want to go, not at the big rock!