When I started as a Private Teacher 8 years ago, I perceived it as just one more way, how to get money, but luckily I had something unique in me that shifted my "do-for-just-money" into luxury lifestyle education business.
If someone here provides some service, I think my unfoldment of that "something unique" will be useful for them:
1) Not what you teach, but how you teach.
Sometimes I don`t know answer, and I`m honest. I ask student if he/she has ideas. Of course they start to have them when there`s opportunity to show off.
And when they give not as correct but very smart answer, I write it down and tell to their friends, how genious my student is. 
2) Theory is worthless. 
I use that what I teach in my daily life and teach it from practical perspective. All my fellows who got high marks in theory and 0 practice, failed. They work in MacDonalds, I`m building a luxury brand in their professional field.
3) Wish of client comes first, if it can`t be fulfilled there`s definately more wishes what you can fulfill, just listen and remember right ones.
Good luck in providing excellent service and making clients happy to work with you!