Depends on how ready your legs are but Squats is King!
If you can't squat yet do lunges.
See I beleive you need to get a totaly balance going and stability so a squat or lunge free weight only type routine I believe will force you to get balanced between the 2 legs.
If you go the leg curl route or leg presses I would do single legs both at same weight until they are balanced, also if your going this route you might wana hit the Multi Hip Machine and ad and abductor machines to balance your self out.
If you can squat and lunge even if it's starting out real light I'd go that route!