MyDay Hi! As someone who did 1/2, hopefully I'll be able to offer some helpful advice
I agree with Lemondade_222 about reading the study design and learning the Kanji required. Though it is tedious, I would recommend learning how to at least recognise and read all 200 Kanji on the study design, this could be practiced by writing them out repeatedly, etc. Learning all the kanji early on is probably one of the easiest parts and it will leave you more time to study other things during the year such as grammar.
I am unsure as to what you mean by enhancing writing, but nonetheless, I would recommend learning how to write different forms in Japanese: e.g. letters, news reports, emails, diary entries, etc. Most forms will have slightly different intricacies to them, such as formality, language used, etc. All that is really needed for genko youshi is to briefly touch up on the writing rules for it. Such as leaving an empty square to the left of your first character in a new paragraph, things like that.
Good luck with units 1/2! Feel free to ask more questions if you need any clarity about my response and such