Lots of people walk their dogs along here so if you have a dog, bring it along for the walk. Make sure you walk to the end. This one should be easy enough to find. Just be careful of the muggles that can just all of a sudden...appear. 
Because there are times when we have some bad weather, I tried to find a spot that would get as much protection as possible. It's also hiding inside something that appears fairly natural. You will find it just a few steps off the path. I don't think muggles would see this but I'm sure you will. It's not big enough for a writing stick, so make sure you bring your own.
I hid it in the most sheltered spot. Look for the big log which is a Nurse log? Right in front of the baby tree, (on the water side) there is a little stump coming out in front of the log. It's under that.