If you are solicited by students outside your office hours and you are busy with your own classes and researcher, decline politely and tell the students that they need to request my permission to discuss with you outside your office hours.
Let me know immediately in case students in the class are abusing your time and/or patience. You may choose to give the name or not. It is up to you.
Start grading the homework immediately . We should never take more than a week to grade a homework. If you need help, let me know immediately. If you are sending your feedback to the students by email, keep a printed copy of your message and evaluation for the record.
Keep a log of how much time you are spending on being a TA and on what specific tasks. I need to make sure that the load is reasonable. If you are being particularly ineffective, then we may consider assigning you to a task at which you are more skilled.
Be at your desk during office hours. Students will complain if you miss only once, only for a few minutes. Leave a note on your desk if you are not there clearly stating when you'll be back. If you need to cancel your office hours, you must let the instructor know in advance and try to arrange for a replacement.
If regular meetings with the instructor are scheduled, never miss the meeting unless you inform the instructor in advance.
Remember that your performance will be evaluated and that the continuation of your assistantship is predicated upon: your academic performance (i.e., your GPA and your research progress) and a good evaluation by the instructor (who may rely on the students feedback).