A couple of lectures on my reading list were about writing rules, so I used them as a basis while writing my own. I also had rules from other games in front of me while writing my own. It wasn’t a long process, because before writing rules down I had first two playtest and I already knew some small issues that I needed to mention.
Among the tips for writing rules, there was one handy about giving an example round, if your game is hard. And I sort of based my rules on that.
Through the course of the project, my rules didn’t change much. I made some minor changes in phrasing, names of cards and numbers, but overall they stayed the same.
After packaging was done, I started designing rules. And I started with some rough ideas and sketches of some “creative” rules design. However, I quickly understood that it is better to keep it clean and straightforward.
I was thinking about handwritten titles, textured backgrounds and binding. At some point, I felt that maybe cards can be useful. But this was all me trying to make complicated things, while rules need to be just clear and readable.
At some point, I thought that it might be smart to include a link to video rules explanation or a PDF of rules instead of putting a booklet into the box. This, however, proved ineffective. Rules are an essential part of the game, and not having them in the box might lead to weird complications. Also, my rules are written in the style of reading and playing at the same time. Which means video rules won’t work. 
After a couple of trials and after I chose the format of long concertina, I’ve talked to my friends from Graphic Design and asked them for help with typesetting the whole thing. They gave me some tips, which made it easier to work. I did a simple layout at the end, but I think it’s better for the game and for the players.