To hear the names, praises and stories of Lord Vishnu and chant them
To remember Him, to wait upon Him
To offer worship and salutation to Him
To dedicate one's actions to Him
To cultivate friendship with Him
To offer one's own body as well as one's dependents and belongings to Him
If devotion is practiced by a man as something already offered direct to Lord Vishnu, I reckon that devotion to be the highest form of learning.
(Vishnu appeared as Narasimha to save young Prahlada from his evil father.)