How to get better at writing?

Keep a notebook or journal close to your bed (something that you can physically write in with a pen or pencil), and write in it twice a day. If you write at least one sentence or short paragraph before going to bed and another after waking up, that is a lot of extra practice over time. It doesn't have to be anything profound or meaningful, as long as you are writing something. You could even use it to copy down any interesting phrases or sentences that you come across while reading, and maybe play around with the sentence structure by changing certain words. On top of the extra practice, it will let you track your progress as you develop your skills.

I suppose, like with any language, the best way is to immerse yourself in written English as much as possible. Read as much as you can (books, social media, instruction manuals, anything!) , and have written conversations with native speakers who can pick you up on mistakes!

Immersion and real practice is the best way. The way I became fluent in Arabic and English is by listening and using both in my daily life growing up. I'm only capable of speaking like native speakers because of these two things. My Arabic skills are worse than my English skills because I don't have as much experience with it. So a lot of times, when I try to convey a message in Arabic by using phrasing that I haven't heard before, it ends up sounding weird. This is because I haven't immersed myself as much with Arabic so I can't produce phrases that sound correct 100% of the time. On the other hand, I have a lifetime of experience with English which allows me to understand what sounds natural and what doesn't.

Looking as well for a better method to improve writing without using ChatGPT

As for me, I’m sure that my writing skills still need to be improved, but I’m not afraid of writing with any length anymore. First and foremost, starting to write is essential. Journal helps a lot, at the very beginning I just wrote short expressions. However I learned many expressions such as had my runs or specific name of cuisine I ate that day over time. What’s more. Keep writing is also helpful, in the four sections of language skills, the more you use the better understanding you will get. I texting with my English native friend regularly, scrolling through Reddit to see if there is anything I can comment on, sometimes I even chat with ChatGPT or writing on my laptop. When you integrate writing into your daily routine, you might probably get better at writing.

Read some books (or even short stories) in English and then try to describe the events of your day in the style of each author. You can even try writing your own short stories if you're a creative person! You'll learn a lot about style, vocab, and the artistic side of writing. A lot of learners focus on precision and rules but English (as used by native speakers) is much less rigid and idiomatic. Don't focus on 19th or even early 20th century authors, if you do this. One shall find, perhaps, that the fashion of discourse has changed somewhat since their time. You don't want to end up writing like a robot or an 1800's ghost with a transatlantic accent. As others have said, the best way of learning is often simply doing. Read and write with intention and your own writing will improve, too.

Well, stop using ChatGPT and correct them yourself, that would give you practice. Getting better at writing is the same for learners and native speakers: you need lots and lots of practice.