G- Giving, U - You, R - Real, U - Uprising
That is possibly the best you can explain to a teacher. The best teacher is the one who is a self preacher. Teaching by command. Guru should be able to make you understand, what to do, and how to do it. But most importantly, should let you know "What not to do". When we know what is wrong, we will automatically be on the right path.
Lastly to summarise "Guru re deva, guru re Vishnu, guru re Devo maheshwarah...guru re sakshaat par brahma, tasmayishri guruve namah"...