They need to be flexible in the shaft since the players swing speed will likely be slower than a more advanced player, so inexpensive new clubs with a regular flex of soft flex are a wise choice. Stay away from graphite shafts for the beginner. Steel is best here. Cavity backed irons are a better choice than forged irons since they are more forgiving. Used clubs can be hit or miss if you don't know what to look for. Golf big box stores are a good place to find a wide selection of clubs but don't let the salesperson make you overspend. Not necessary at this stage of development for the player. The best place to spend money for a beginner is on golf lessons from a golf pro.