Your tagline will be seen at the top of your profile and on every piece of content you add. It's often going to be the first thing that a potential customer reads about you, so you'd better make it count!
The photo below shows the position of Elephant_Walker's tagline on a Listing he added.
Tips on Writing The Best Tagline
Mention the area in which you operate.
Make sure to use proper grammar.
If you have a focus on a certain type of service, mention it here. Remember, in some cities there are many tour guides, so you have to do your best to stand out. For example, "Take a Tour Through the History of Beijing" would be a good tagline.
If you have a specific competitive advantage, try to list it in your tagline. For example, Lijiang Guides used the tagline "Travel in China with a native-English-speaking expert on SW China". One of the benefits of traveling with him, is that he is a native English speaker and he makes that clear in his tagline.