The American Red Cross website offers general guidelines for donating:
Be in good general health and feeling well.
Be at least 17 years old in most states (16 years old with parental consent in some states).
Weigh at least 110 pounds. Additional weight requirements apply for donors 18 years old and younger and all high school donors.
Have not donated blood in the last 56 days.
Also according to the American Red Cross website, here's what to expect at the time of donation. The entire process takes one hour.
Registration — Sign in, show an ID, read required information.
Health check — Answer questions online or in a private interview, and receive a general a mini health physical.
Donation — Sit comfortably while a pint of blood is drawn. The donating part takes eight to 10 minutes.
Recovery - Rest for 15 minutes and enjoy a snack.
Testing — Blood is tested and then sent to a patient in need.
For more information, visit www.redcrossblood.org.