I am teaching myself Japanese. To begin learning how to read and write in Japanese, I have started my studies with Hiragana. I know that I need to have specific proportions to make sure what I am writing is accurate and legible. However, the only paper I have at hand is lined, and I am not sure how I should know if my proportions are correct. Should I start getting graph paper to practice?
Graph paper might indeed be helpful, but just by being mindful of the proportions and flow you have already made a step that few ever do.
Ultimately, for legibility, the most important thing is that the characters are distinct, not so much that they adhere to form, but what I would recommend is getting any one of a great many books that focus on writing legible kana.
Simply getting graph paper is unlikely to help much if your form is sloppy to begin with.