Go through the South Gate entrance as it's very convenient and quite spectacular. The wall is very wide and even if there are a lot of people, it still feels easy to walk around and enjoy. There are great views of the city from above. I recommend going in the late afternoon so you can catch some daylight but also be on the wall when the lights get turned on. Renting a bike is super easy and you can choose from single or tandem ones. We did the whole wall (almost 14 km) on a tandem bike and it was such a beautiful experience. It's a bit windy up there so make sure to bring a hat and a jacket, especially if you plan to ride a bike which I truly recommend.