The only pimples that are (relatively) safe to pop are whiteheads. Painful cysts or boils are too deep to drain by yourself and can scar.
Wash your hands and face; swab spot with alcohol.
Dip a clean needle in alcohol and gently pierce the whitehead. Try not to draw blood.
Gently squeeze from either side using hands or Q-tips. If it doesn't come out easily, stop. Squeezing too hard causes scarring.
Cover with a Band-Aid to prevent scabbing.