Kartik is the best, the purest of purifiers, and most glorious of all months. Any vrata, even the smallest, will yield huge results. During this month, it is recommended to hear Srimad Bhagavatam, daily in association of exalted Vaisnavas, if possible. It is most benificial to recite and read Gajendra Moksha Lila-stava from 8th canto of Srimad Bhagavatam, which teaches complete surrender/dependence on Supreme Lord.