It depends on the need of each individual student and how fast he/she wants to start speaking the language. Some students take 1 lesson weekly, some even more than 2 sessions. As for the length of the lesson, I highly recommend 90 minutes, because in my classes we speak a lot and in 60 minutes it's not usually possible to accomplish everything we need to. :-)
The very first thing I focus on in my lessons is pronunciation and spelling, so the student can start reading very quickly and expand his/her vocabulary. I have developed several tricks to help my students to understand the grammar better.
I always disscus the materials and text books with my students before we start our lessons so they can decide, which ones do they feel the most comfortable with. I like to use a very good textbook which I recommend to my students in case they don't have any specific preference. I also use magazines, audio and video materials, flesh cards, games etc.
I like to assign frequently a short homework in the form of several sentences to translate and then during the following lesson we discus and correct eventual errors with the student.
I challenge not only the advanced students, but any student, because everybody needs to see his/her progress no matter what level they are at. I usually let my students to pick the topic they want to talk about during the next lesson and I ask them to write a short essay of their choosing giving the student the option to grow their knowledge further.
We talk about various topics and about the real life, so each student feels more confident to communicate in that language. We play games and I love when our lessons are full of joy and laughter.