1- Select which base you will use for your server. MartySama or Owsap are the best known and most reliable currently if you want a stable and secure server, but they also have TMP4 reference server files that are free and available here on the forum.
2. Plan exactly how you want your server. Experience, Drops, Maps, Dungeons, Events... everything...
3. Do you want to add new systems? Whether to improve gameplay and QoL, server protection, new content in general. There are many here in the group that are 100% free, but there is also the option of purchasing systems made by developers here in the community around the world. Avoid using any leaked material on the internet, in addition to taking away the support of serious developers, they usually contain bugs and errors that were intentionally made by scammers and if you don't have enough knowledge in programming, you will have to hire them again to correct the errors For you, this opens a huge gap for them to steal your files.
4. When you have a base ready, you can open the server for testing by hiring cheap VPS hosting.
This is a very short summary. We still need to talk about autpatcher, protections, web page, etc.
I started studying programming and developing my server about 1 year ago and gained a lot of experience and knowledge here in the community. If you need any tips let me know and I can give you some.
My discord: rt_ballads