I popped a pimple on my chin, and puss came out, then a little while later a clear fluid started coming out-a little bit at a time, what should I do?

Keep it clean. Wash it with soap and water to prevent secondary infection. The clear fluid is normal serum/tissue fluid. Apply pressure and it will subside.
Leave it alone. Popping pimples is generally not a good idea. The fluid is liquid part of blood and will cover the wound. If you have pimples you may consult this site for home treatment. http://www.webmd.com/skin-problems-and-treatments/acne/acne-vulgaris-home-treatment.