Writing looks like the wrong tool if your goal is conversation. It is actually the cheapest way to rehearse the exact sentences you will need, with the pressure removed and time to notice what you cannot yet build.
Writing is speaking with the clock stopped
In conversation you produce a sentence in a second and never find out what was wrong with it. On paper you produce the same sentence with ten seconds to think, and the gaps become visible. Those gaps are the same ones that make you hesitate out loud. Finding them slowly is how you stop tripping over them quickly.
Write about your own day, not about topics
Three or four sentences about what you did, what annoyed you, what you are going to do tomorrow. This is the material real conversations are made of, and it is the vocabulary you will actually reach for. Essays about abstract subjects feel more serious and teach you words you will never say aloud.
Say it after you write it
Read each sentence out loud once you have finished it. The point is not the text — it is that you have now produced that sentence twice, and the second time it went through your mouth. A written sentence you have never spoken is still only half learned.
Mark what you avoided
You will notice yourself going around a structure you do not know — simplifying a thought because the real version was out of reach. Underline that. The list of things you avoided is a far better study plan than any syllabus, because it comes from something you genuinely wanted to say.
Five minutes, four sentences, read aloud. It is the least glamorous habit in language learning and one of the few that shows up directly in how you speak.