Read articles in the target language
If you are a beginning or intermediate student with a new language, pick up a newspaper or magazine in the target language, and choose one article that looks interesting.
Slowly work on reading that article and learning the words that you didn’t know. Similar to my points in other posts about movies or music, choose a style of magazine or newspaper that you would read in English anyway.
The value of reading in the target language is inestimable. It is difficult, sometimes it looks like all ‘Greek,’ but it is tremendously valuable. It gets the language in your brain, even at an unconscious level. As you read, you will sound out the words and store their forms/meanings in your memory. The more often you do this, the more automatically their forms/meanings will spring to mind.
Unless you are a complete beginner, I recommend this to all of my students because there is something special about reading authentic material in the target language–language that is not written for students of the language but written by its real users for its real users.
If you are not sure what paper/magazine to look for, just google “[French] weekly” and follow the results. If you are improving your English, look for something like Time or Newsweek. The attached picture comes from my favorite Italian newsweekly, L’espresso.