Before I get into answering your question, an important distinction (telling the difference between two things) needs to be made. "Learning" and "memorizing" are not the same thing. Before memorizing, a word should be learned. Learning usually comes from exposure (contact with) to new words. Personally, I read to learn new words, but not everyone does this the same way. How do you learn words in your native language? Try doing the same in your target language. Now, as for memorizing words, it depends on what you're trying to memorize. If it's something of a common noun, I tend to just use pictures, not translations, to identify words. This also helps with thinking in the target language. It should be noted, however, that simple images are not nearly effective as elaborate ones. It might be worth your time to look into "visual mnemonic techniques for memorization." A quick search should help you find what you're looking for. For words that are harder to visualize, I imagine their components or related words; synonyms. Additionally, I do this with the use of a spatial repetition system called Anki. It's free for the computer and Android devices. It's really worth a look into if you haven't heard of it already.

I love the aplication and website "memrise", especially when I can make my own words list. If you prefer classic ways of learning I highly reccomend making flashcards - pieces of paper with the word in your target language on one side and definition/ other language on the other side. The rule is that you take, for example 20 words and chceck.if you know what they mean. If you can answer, what does the word mean you put it aside, if you don't - you put it at the end and then repeat again, until you know its meaning. (the applications works exactly the same ;)