Consider where you are in your graduate program. Do you need to make progress on your research, or can you afford time away from it?
Step2
Look at the details of the specific TA job(s): What's the pay? How many hours per week will you have to work?
Step3
Meet with the professor teaching the course to ask any questions you might have. Also think about whether you have a good working relationship with the professor.
Step4
Think about other job opportunities. Consider nonacademic jobs that you're interested in and that pay better.
Step5
Evaluate your teaching portfolio. Do you already have a lot of teaching experience, or will this be a rare opportunity to gain some?
Step6
Consult with your advisors, who should be able to offer you helpful advice that's tailored to your circumstances.
Tips & Warnings
Remember that being a summer TA can be intense, with two to four hours a day in the classroom, plus preparation and grading. Depending on your personality and experience, this could be good or bad - or neither.