Hmm, is this inside, like warehouse, forklifting, or outside forklifting? I know in the warehouse I was in charge of for a bit we'd train in-house. I think, regardless, toss some pallets on the ground and just practice getting in them, lifting them safely and moving them around, empty pallets add a bit of challenge because they are light and you'll move them easily unless you do it just right. Also, it's good to get used to being extremely close to things without hitting them. The back wheel steering takes a bit of getting used to so maybe just drive around too. Forklift driving (I have a lot of experience on small forklifts) is a lot of fun, can be quite stressful, and makes you think. It never hurts to toss a long load on the forks to see how to negotiate your way around things as well. Take your time as you learn, you'll be surprised how quickly it can be picked up but slow and steady will keep you and others safe, as long as you are paying lots of attention.