Midjourney runs through Discord, and here you can learn how to quickly set it up. The commands you give it are called "prompts". Writing a more specific prompt will generate better results (up to a point, of course). Prompts are pretty straightforward to write.
However, good prompts are not simple sentences because communicating with Midjourney is a bit tricky. It doesn't exactly speak Oxford English. According to the creators, it doesn't understand grammar, sentence structure, or words like humans do. They recommend using more specific synonyms to get better results, such as "gigantic" instead of "big" and removing words when possible. What’s more, while commas, brackets, capitalized letters, and hyphens will help you organize your thoughts, Midjourney is not capable of reliably interpreting them. However, it is worth mentioning that version 4 saw a slight improvement in its capability to interpret traditional sentence structure.
Do not worry, there are also more advanced commands you can use to master the art of prompting and make Midjourney your “puppet” (sounds more evil than it really is, promise). These are some of the parameters we found especially useful:
- "--no" to exclude a specific thing and to prompt weights (and negative weights) to give different importance to different aspects of your artwork;
- "::" to separate prompts;
- "--ar" to set the aspect ratio of the render;
- "--seed x" (where x is a number) to force consistent results (very useful when comparing slightly different prompts).
Image prompts are also a thing - if you can't tell Midjourney what you want, you can always show it. It will understand what the image contains and combine it with your text prompt to give you satisfying results.