As a teacher, dealing with the money is usually kind of awkward, and sometimes seems like it is in a bit of bad taste. We are making music, not running a sausage shop. Even so, we can't avoid it, we've grown attached to things like food and a roof over our heads. I recommend either making an agreement to get payed in advance for lessons monthly or bi-monthly. In any case, I try to avoid the actual daily cash transaction; a closed envelope works well, or just leaving the money on the piano, a table or the mail slot works as well. Chopin asked his students to leave the money on the mantle and was actually pretty offended when any of his students tried to give him cash directly. I am a bit of that mentality as well. It might be old-fashioned, but to me it doesn't feel completely right dealing directly with the cash after every lesson.