Not really a tip for hole 18, but after finishing 18 you are a long way from the start. walk past the mini golf back to the road. turn right up the hill and you will eventually get back to the start.
From hole 11 basket, go across bridge. stay to the left (you will be walking near/on the fairway for hole 13) keep creek on your left and you will see tee for 12.
Signs for start of course aren't great. As you enter park, Hole 1 is located to the far left of the tree-line across the parking lot from the pool. It is near a picnic table.