Hakim al Ummah Mawlana Ashraf Ali Thanawi (Allah have mercy on him) said,
‘To achieve strong nisbet (an experiential mutually friendly relationship with Allah) and perfect unison (wusool) the (the specific sufi methods of) remembrance (dhikr), spiritual exercises (ashgal) and meditation techniques (muraqabat) are needed.
It is highly recommended to acquire them.
The minimum criteria for being given ijaza and functioning as a Shaykh is acquired by achieving a strong nisbet,
Shariat wa Tariqat, page 51