Grab some objects such as small blocks of wood or pieces of paper and place them on the ground in some random spots. Practice pulling a wheelie and setting the front tire down on each object and stopping. This will help you work on tire placement such as on a log or approaching a rock. Tire placement can come in handy and it looks simple but you will miss the markers the first few times you try it. I have illustrated what I mean in the picture below. Mix it up and throw out random markers to land your front tire on.
The other thing I would suggest is hopping off the bike while its in motion to the left and then hopping back on then hopping off to the right all while running next to the bike. This will give you some confidence in getting off the bike in an emergency so you don't get caught up on the bike. This one gets tiring but really helps you gain some respect for what the bike is doing underneath your body.
--Biff