Mnemonics are memory aids that connect new information with imaginative metaphors, vivid examples, stories, visuals, etc. For example, associating the russian word
мост [most]
(bridge) with a phrase like "The bridge is the
most important part of a road" helps cement it in memory. The association must be meaningful to you personally and connect to some previous knowledge. This video
gives a clear explanation of mnemonic techniques:
Khan Academy "Encoding strategies"