What’s a good way to start writing what I know in sentences? To sum up, I’ve opened level 8, and I use bunpro for my grammar usage, which is finally getting easier. I’d like to start writing, even though I’m not expecting an easy time for a while. Would copying other sentences from books and such things be a good idea? Although particles are still difficult at present. This adventure has been fun and I don’t mind the challenges that still await me. Thanks
If you just mean the act of writing (Hiragana, Katakana, Kanji) so that it looks decent, then copying text is also totally fine. Be advised that handwritten text might look different from computer fonts, so take care to not copy a computer font too much.
If you mean writing freeform to practice output, the absolute best is if you have someone to check your writing. It can be a Japanese friend, a class teacher, or an online tutor. Once a week should be enough to check all your writing in the beginning and provide feedback.
If you don’t want someone to check your work, I’d recommend getting some exercise books with answer key and doing that. If you don’t have the same answer, it doesn’t mean your answer is totally wrong, but it indicates that a Japanese person might phrase it differently, and you will learn some typical patterns as well.