I will not say I know everything about worldbuilding, but I do have a good knowledge of how to so light worldbuilding, like that of Harry Potter, and Hard worldbuilding, like that of The Lord of The Rings. (Please note that in this I will be using Medieval Fantasy as my base genre, the information applied in this can be used for other genres but not as well as I will be using it in fantasy. Though I hope to be able to write this in such a way that it can be applied to most genres.) I recommend using a notebook to do this worldbuilding so it is all stored in one place.
Creating a World
In creating a world there a couple of things that have to be considered. Number one being, how large is the world. This might sound like common knowledge, but it is something that most people skim over when writing. The size of the world can effect how the story plays out; if it a large world, then it will most likely be a larger book because of travelling. If it is smaller, then it will most likely be shorter.
Now that's done we can get onto the main part. Map design. I recommend when making your world just getting some standard paper or notebook and drawing out some versions (about 2-3) of what it would look like. WASD20, a youtuber, has a great collection of videos on how to draw these types of maps.
Will your world have hills, mountains, secret doors in cliffs. if so draw these into your map. You don't have to be an artist to do this, I am not, but I can understand what's going on and that is all that matters.
Now that you have the world drawn out, pick the one you would like, then photocopy it. I do this to understand where my characters are and are going in their journey. Draw out in a coloured pen a line to show the route they will take. This just helps in remembering where they are.
Great! you have a map with a journey line, but now we have to think about some of the more troubling matters. The small details.
Locations and Architecture
Most locations, such as ruins or forest, you can make up as you go along; but some locations, such as castles and cities and important locations, have to be planned out. Let's start with the castle/city. Assuming that your story has one of these, get your notebook and start mindmapping: where is it?, will that effect the look of the place?, who lives there?, and so on and so on.
Here is a look at what on could look like:
Fahdag < Mountains Carved walls
built into the walls > Grey Stone
A couple of things to think of as well is the technology that they use, is it good, what's it like? Stuff like this can really give a sense into what era you are designing and what type of language and life they lead.
Again I recommend drawing these out in rough sketches in a notebook to better visualise. They do not have to be masterpieces, just enough to get the message across.
So by now you should have a good visual aid to creating your locations, use these to your advantage.
Like everything, there must be a history behind things; whether that be how the world was made, or how it gets its energy, or how a thing was made and the wars fought around it.
I recommend getting the main thing in your world, for me its the crystals, and write out on word a small one page brief of their history and what happened. You do not have to do this for every little thing in your world, but the main things, this will help.
Please note though, Do not info dump this info into your book. The history should be weaved into the story instead of put right in front of you.
So now you have drawings of locations, history written down to reference. USE THIS TO YOUR ADVANTAGE!
Very Small Details:
Now we get into the last parts of worldbuilding, the very small details.
Religion/ culture/ rituals
Like with any civilisation, there are rituals, and religions that exist. You do not have to put any of this into your story if you do not want to.
In your notebook write down what the religion might be called, then brainstorm some rituals such as, on the second month of every second year, they sacrifice a goat to the sun god for good crops.
Every world needs a way of exchanging things, so make up your own currency. think like harry potter and GoT; be as weird of as basic as you want with these. As previously said, I recommend putting all of these ideas into your notebook.
In total, I have only covered the basics of worldbuilding and you can take this a far or as little as you like. Please remember to write everything down in your notebook. Have fun worldbuilding and I hope your novel is great.