What is the difference in complications or approach for a first time cesarean section, and the second or third one?

Scar tissue: Scar tissue from a previous csection or any other pelvic surgery can make a repeat csection more complicated and difficult. It may take longer to do and their is a slightly higher risk of injury to mom's surrounding organs. If the placenta implants over the previous uterine scar, it may not detach at delivery causing mom to bleed and need a hysterectomy. Even so, most repeat sections go well.

Incrementally worse.: The first c-section should be pretty safe; the second usually almost as safe. The third and beyond c-sections get too risky for mother and baby and should be avoided with proper contraceptive techniques.