Midjourney is a popular AI image generator that allows users to create high-quality images with unique styles and compositions. To use Midjourney, one must sign up for Discord and accept an invitation to the Midjourney Discord channel. From there, users can access various commands, including `/subscribe` to activate their paid plan, `/imagine` to generate images, and `V1, V2, V3, V4` buttons to create variations of their prompt. Users can also edit their images using upscale and variation buttons, and save them for later use. To get the best results from Midjourney, users should be specific with their prompts, consider details such as subject, medium, environment, lighting, color, mood, and composition, and play around with parameters to set key details like aspect ratio and randomness. Midjourney has a lot of powerful features, including image references, style references, remix mode, and multi-prompts, which can be discovered through the help docs. As Midjourney is still in beta, users should stay tuned for updates and new features.