Now that you're familiar with Grease Pencil, we'll illustrate an alien denizen of the stars, starting with a solid rough draft. Don't sit down and expect a good drawing to instantly flow out of your stylus. Instead, we'll begin by researching and experimenting with a design, drawing things to see whether we like it, and refining the rough character.
In movies, a cool alien design is often the best part of the film, and variety makes for a dangerous and interesting cosmos. Is your character a muscular warlord, or sophisticated ambassador? What real creatures and organic forms do they reference? Biped or quadruped, mammalian or reptilian, or perhaps floating through the air with an unseen energy? Design elements such as weaponry, biology, and fashion can give it a dynamic silhouette, and imbue them with a sense of history and culture...