The way to the great wall is easy to find. There is only one sign at the very beginning and that is it. At some point, we came to a sign, which says "No strangers allowed". So you have to turn back. The only tipp we had was only that the road went up. At some point you start seeing red ropes tied on the trees to show the way. At some points, you will find red ropes and an arrow. In time, we developed a sense, in which an arrow means climb :).
This road is for people who has a very good body shape. I would strongly suggest to take:
1. a lot of water (at least 2-3 Liters)
2. A map, a phone with kommod or openstreetmap. Google is no good in china.
3. A cap (if you choose a sunny day)
4. Sun cream