What further practices can enhance self-inquiry beyond asking 'Who am I?' for fifteen minutes?

According to Osho, first do the fifteen‑minute ‘Who am I?’ earnestly every day for two to three months; your inquiry will ripen and new questions will arise. Then deepen it by entering intensive meditation camps and a sangha-like atmosphere where everyone practices. This collective field, plus personal responsibility (not waiting for another’s grace), gives the initial momentum that transforms self‑inquiry.