Part 1: Should I make a server?
This is an important question. Just because you can make a server doesn't mean you should. When you're making your server, make sure to ask yourself these questions:
Is this something that you are passionate about? Don't make a server just for the sake of making one. You should be highly interested in the topic and want to improve the community for that topic. You should also be knowledgeable about the topic and able to help newcomers and experienced members alike.
Does this server have one specific topic? If your server is a "generic gaming server" or "generic public server" or "random server" or "memes" or any variation, then it is not going to grow. Frankly, no one is interested in joining a server that doesn't have a defined topic. If you take a look at the biggest and most-popular servers on Discord, they all have a specific topic, like "Overwatch" or "World of Warcraft Druids" or "Discord API". If you want your server to become popular, you must pick a specific topic.
Do any other servers for this topic exist? Once you've decided on a topic, you need to figure out if a server for that topic already exists. For example, don't make a server about "League of Legends," because one already exists. If a server for your topic already exists, you should join the existing server and contribute to the existing community instead of trying to create a new server for the exact same topic! However, it's possible that there doesn't exist a server for "League of Legends Demacia Lore," so that would be a perfectly-fine topic to create a server for.
Does the topic benefit from having a Discord server? For some topics, there is no benefit to having a Discord server. Discord is great for real-time communication via text and voice. Make sure that the topic is one that can be discussed in these ways.
Do you need to own the server? This is probably the most important question. Obviously, you're here because you want to set up a server, advertise it, and grow a community. The question is, would you be willing to give ownership and all permissions to someone else if it meant that the community would grow better? If you would not be willing to give ownership to improve the community, you need to stop reading this guide right now and delete the server. Servers aren't things to "show off" because they are popular; they are communities of real people that want to communicate, and you need to care more about that community than about who "owns" the server itself. This is something you must accept if you want to create a community: that if the community would do better without you, you need to be able to give it up to someone who will perform better.
If you've answered these questions according to the guidelines, you're ready to start setting up the server!