I start with Mineral Spirits and an old Cotton 'T' Shirt. Evaluate progress as you proceed. Turpentine works, too. Continue until 'grunge' is gone.
If you like how the wood is looking switch to several hand-rubbed applications of 50/50 mix of linseed oil& Turpentine.
Buff dry with soft cloth, then, finish with Howard's Feed & Wax or Pledge.