I'd start by mentioning the fact that you get your own World, with its own history and geography, all for yourself.
Then, for fortress mode (which, I guess, will be your biggest concern here) I'd organize it in a way where you:
1. Describe what you want to do in a natural way.
2. Translate those orders into the game.
This should make your guide more easy-going, more atomized, and easier to look through. For instance:
1. I want to grow crops for food, as it is a reliable, inexpensive food source. The most basic food crop in DF (and arguably the base of dorf diet) is the plump helmet, which one can use to eat raw, cook, or even make alcohol. For this, I'll tell my farmer to prepare the soil and then tell him to plant plump helmets all around the year, which he will harvest when they grow big enough.
2. Farm plots have to be built like a regular building. I'll go to the build menu with
b -> p to designate a farm plot. I resize it with the u/m-h/k keys and I place it underground, in an area with soil. A 3x3 farm should do for now. You can see the farmer building it shortly after. Then, I use the building selector with
q and plant stuff on it. Scroll around each season with the appropiate key and select "plump helmets" for every one of them with the
-/+ keys and the
return key.
Please remind your readers that if their dwarves don't dehydrate and die in your first fortress and starve to death in your second, they're probably not playing the game properly