As my experience Japanese is a hard language to write but really simple to speak many people that live in Japan can speak really well in Japanese but they cannot be able to write almost anything. I think as the other person say focus in hiragana and katagana and then you can continue with the Kanji (chinese characters).
Other thing you need to have in mind is the order in the sentence. meanwhile most of the western language are SVO Japanese are SOV that means the verb is always at the end of the sentence.
Dont be frustrated about the writing system cause as I said before the pronounciation and grammar are not so difficult just different as european languages.
Usually the book usually all recommend is Minna no nihongo.
I hope this help you.
I would start with learning kantakana. You can practice that athttps://realkana.com/. https://www.tofugu.com/japanese/ has in depth guides to things you can do and study to become more proficient and gain more knowledge.
https://moonprincess.tumblr.com/languageresources that one is kinda a back alley. It has some books that a lot of people recommend to buy suck as genki I and II as well as japanese for busy people. this includes workbooks. Ive personally downloaded using the site and it seems safe as I scanned the files beforehand. of course alway be cautious of links and things you download.
youtube has alot of great videos that explain things like grammar and sentence structure that ive listened to. most of them are done by japanese pod. Theres plenty of material out there just gotta take the time to find it.