Most important qualification

Dattatreya speaks to Parashurama (from Tripura Rahasya 35-45):

tatrādyaṃ sarvamūlaṃ syānmumukṣutvaṃ na cetarat |
mumukṣāmantarā yattu śravaṇaṃ mananādikam || 35 ||
na mukhyaphalasaṃyuktaṃ kevalaṃ śilpavad bhavet |
na śilpajñānamātreṇa prāpyate paramaṃ padam || 36 ||
mumukṣāmantarā yaistu śrutaṃ samyag vicāritam |
śavālaṅkāravat sarvaṃ teṣāṃ vyarthaṃ bhavet khalu || 37 ||

The most important, the root of the qualifications is the desire for liberation, mumuksutva. Nothing can be achieved without it. Study of philosophy and discussion on the subject with others are thoroughly useless, being no better than the study of arts. For the matter of that, one might as well hope for salvation by a study of sculpture and the practice of that art. The study of philosophy in the absence of a longing for salvation, is like decorating a corpse.

vyarthā sāpi bhavenmandā mumukṣā rāma sarvathā |
yathā phalaśrutericchā sāmānyā na phalāvahā || 38 |
phalaśrutyuttarodbhūtā necchā karmaphalāvahā |
phalaśrutyā kasya nāma na syāt sā jīvadharmiṇaḥ || 39 || 

Again, o Parashurama, a casual desire for liberation is also vain. Such desire often manifests on learning of the magnificence of the liberated state. It is common to all but never brings about any abiding results. Therefore a passing desire is worthless.

tasmādāpātarūpāyā mumukṣāyā na vai phalam |
yathā mumukṣā tīvrā syāttathā tasyā'ciraṃ phalam || 40 ||

The desire must be strong and abiding, in order that it may bear fruit. The effects are in proportion to the intensity and duration of the desire.

mumukṣā yā mukhyatamā sā sādhanagaṇeṣvalam |
pravṛttimutpādayed vai sā hi tatparatocyate || 41 ||
yathā sudagdhasarvāṅgo na śītānyadapekṣate |
tathā yadā vimuktyanyannāpekṣeta hi sarvathā || 42 ||
sā mumukṣā bhavettīvrā samarthā phalasādhane |
eṣā vimukteranyatra doṣadṛṣṭyaiva jāyate || 43 ||

The desire must be accompanied by efforts for the accomplishment of the purpose. Then only will there be concerted effort. Just as a man scalded by fire runs immediately in search of soothing unguents and does not waste his time in other pursuits, so also must the aspirant run after emancipation to the exclusion of all other pursuits. Such an effort is fruitful and is preceded by indifference to all other attainments.

tīvravairāgyamukhataḥ krameṇa tīvratāmiyāt |
doṣadṛṣṭyā hi vairāgyaṃ viṣayaprītināśanam || 44 ||
vairāgyeṇa mumukṣutvaṃ tīvraṃ tatparatodayam |
tatparatvaṃ sādhaneṣu pravṛttiratitīvrataḥ || 45 ||
atitīvaraprakṛtyaiva drutaṃ phalamavāpnuyāt |

Starting by discarding pleasures as being impediments to progress he develops dispassion and then the desire for liberation, which grows in strength. This makes a man engage in the right efforts in which he becomes thoroughly engrossed. After these stages are passed, the most unique consummation takes place.