Read a few screenplays and try and identify the basic plot and story arc within each story. Take a few notes on what you recognize about the story, including location, time period and character personality traits.
Recognize the basic genres and the major differentiations behind each genre. Know that there are about seven major film genres: horror, romance, drama, comedy, thriller, crime and fantasy.
Identify the main theme behind the story you are reading. It is often not fully comprehended until you finish reading the script. Visualize what the movie feels like; horror and thriller genres are easiest to spot because of the ongoing tension.
Be aware of genre mixing like comedy-drama, or fantasy-horror or science fiction-thriller. Try to identify which genre is the most prevalent. Know that fantasy and science fiction are generally the most readily recognizable genres due to their fantastical nature.
Figure out whether the screenplay is one of the less prominent genre subtext. Coming of age films are very popular, as well as courtroom dramas, black comedy, buddy films (usually comedy as well), and musical, westerns and historical genres. Become acquainted with genres by browsing through a website or video store and seeing what type of movies are placed in their respective genres.