I recommend the excellent 2014 book Make It Stick: The Science of Successful Learning by Brown, Roediger, and McDaniel.

Many of these ideas are also expressed by a series of short videos by Prof. Chew of Samford University.
Hyde and Jenkins tested the kind of learning (intentional vs. not) and level (shallow vs. deep).
The shallow task was to note the presence of ‘e’ in word, the deep task was to rate the pleasantness of the word.
Intention had no affect but the level (e.g., pleasantness) did.
Need good orienting tasks to prime deep processing
Things that help learning