Thank you.
In casual daily communications, you may omit 「よろしくお願いします」(yoroshiku onegai shimasu). Japanese parents often use yoroshiku onegai shimasu as a closing phrase at the end of written messages.
Yoroshiku onegai shimasu ("thank you") or sumimasen ga yoroshiku onegai shimasu ("I'm sorry, but thank you") are used when making requests of teachers, while 「お手数ですが、よろしくお願いします」(otesu desu ga, yoroshiku onegai shimasu, or "I apologize for troubling you, but thank you") is used to acknowledge that your request will create more work for the teacher.