I started in August 2018 on a KX450F at 50 yrs old. Not the usual beginning for most but it's just how it happened for me. I don't like track riding and bought a track bike impulsively, not realizing that they're not ideal for trails. I put about 50-60 hrs on the bike, taking 1-2 rides per week on most single track trails and some desert rides. I've got scars up and down my legs from wipe outs on slippery roots, rocks, puddle wipe outs, etc... Being sore is now the norm.
I rode technical trails on a mountain bike for 30 yrs, so I think that definitely helped me transfer to motorcycles.
I think that the rider's personality and quite frankly, balls that determine how they will dive into this sport. It helped me alot to find 3-4 advanced riders that have put up with me on my learning curve. In 6 months, I'm now called an intermediate rider by these guys and I've worked up to some black diamond trials.
You'll get better if you are on the bike, practicing every chance that you get. It's become a passion for me. I sold the KX and got a 2016 Husqvarna FE501S about a month ago. Much more efficient and enjoyable on the trails. Good luck!