How does conlanging work
I am not the best person for explaining this but ill try
You could also watch The Artifexian on youtube, where I got the idea from
I just begin with an alphabet, and build the language around that, though I also sometimes start with an idea for the language, and the alphabet/characters come as I need them.
I mostly just write down random things if I want to, I am currently translating the countries of the world, though you can do what you want.
I also have some (Seissiric, Sierien, Thaelich, Thaos) that are based on actual preexisting languages (German, German, Dutch, Fr*nch) with some changes, (such as changing Tag into Tagos in Seissiric)
I still recommend watching the Artifexian, or a different channel, if you want to do it yourself.