Learn the game. Keep moving. Have fun.
If you are still learning how to play and getting comfortable on the course, fall is a great time to get out there.
If your ball disappears into an area covered with leaves and everyone is reasonably sure where it finished, spend a short amount of time looking. If you cannot find it, take a free drop in a reasonable nearby spot and keep playing.
At this stage, learning how to move around the course, make decisions and enjoy the experience is more important than turning a casual round into a Rules exam.