I used to charge my students...,

[Silverobama]

I used to charge my students on the basis of per hour per session but later I asked my clients to pay me 10 times in advance.

Is this sentence natural if I want to express "I am tutor and I tutor on an one-to-one basis. In the past, I charged the students I taught based on one session, usually two hours. Let's say it was 50 yuan per hour, I charged them 100 yuan soon after we finished the tutoring session. But later I began to charge my students 10 to 20 hours in advance."

 

[tedmc]

No.

I asked my students to pay me at the end of each tuition session, typically 100 yuan for a two-hour session. Later, I asked them for an advanced payment for ten sessions.

Note that "charging" does not mean "receiving of payment".

 

[emsr2d2]

I used to charge my students at the end of each lesson. Now I charge them up front for ten lessons.