How can you improve memory?

Rehearsal
Relates to the Multistore model of memory, which suggests that the more you rehearse information, the greater chance you have of recalling the information.

Similar Cues
Relates to the Cue Dependency theory, which suggests that when memories are formed they leave memory traces, and they can be in the form of state or context cues. State cues refer to the physiological state of an individual (happy, sad etc) and context cues relate to the environment (classroom, inside a shop etc). The more cues present at the time of recall, the easier it is to access the memory.

Minimal Similarity
This is in reference to the Interference theory, which states that information can interfere with the recall of other information. This comes in two forms: proactive interference and retroactive interference. Proactive interference is when old information interferes with new information, and retroactive information is new information interfering with old. This commonly occurs with similar information, so it is better to not learn similar information simultaneously.

Depth of Processing
This relates to the Levels of Processing theory, which states that there are three ways to encode information, which is structurally, phonetically and semantically (in order of worse to best in terms of rate of recall). Structurally refers to how the information appears, such as how a word looks, capital letters, lowercase etc. Phonetically refers to how information sounds, so whether a word rhymes with another or not. The last one, Semantic, refers to the meaning of the information, so whether happy means the same as joy etc. So to improve your memory, you would learn information based on its meaning, over the other two.

Hope it helps, I can go more in-depth in any of the theories mentioned, just ask if needed (: