An excellent* way to learn new words is to make vocabulary cards. The diagrams below show an example using the word cat
Here's how you do it:
(If you write down a verb, it's best to put its infinitive form. So for example it's better to write "to purchase" than "purchased" or "to strike" than "struck".)
* Paul Nation, one of the most renowned researchers in the field of vocabulary learning, states:
"There is a very large number of studies showing the effectiveness of such learning (i.e. using vocabulary cards) in terms of the amount and speed of learning."
Nation, P. Vocabulary size, text coverage and word lists". In: Schmitt, N. & McCarthy, M. (eds.) Vocabulary: Description, Acquisition and Pedagogy. Cambridge University Press. 1997.)