Memorizing sets of items
The literature generally provides strong support for the use of self-testing in cases like this, particularly via the use of flash cards (Karpicke and Roediger, 2008). The efficacy of self-testing for facilitating learning of arbitrary or complex sets of items has been suggested to be driven largely by the combination of two effects: the generation effect (Slamecka and Graf, 1978) captures the tendency for active retrieval of memory (e.g. fill-in-the-blank) information to increase the probability of successful future recall, as well as the spacing effect (Donovan and Radosevich, 1999), which captures the tendency for learning at a moderate intensity over time to outperform learning all at once.
References

Donovan, J. J., &amp; Radosevich, D. J. (1999). A meta-analytic review of the distribution of practice effect: Now you see it, now you don't. Journal of Applied Psychology, 84, 795-805.
Karpicke, J. D., &amp; Roediger, H. L. (2008). The critical importance of retrieval for learning. Science, 319(5865), 966–968. doi:10.1126/science.1152408
Slamecka, N. J., &amp; Graf, P. (1978). The generation effect: Delineation of a phenomenon. Journal of experimental Psychology: Human learning and Memory, 4(6), 592-604.