Just a note, toner is made up of plastic, which is melted into the paper to print in a laser machine. This method uses some of the toner particles that have not bonded to the paper to bond to the fabric. As usual whites and cottons bond best (ie show up the best), but irrespective I use my trusty black sharpie to ink in the outline more clearly.
What you need for this is a stencil or picture that is primarily black and white.Print it out using a photo editing app, where you can make the dots per inch high say 1200dpi, so you get plenty of colour/toner where you want it. Below are examples of stencils that work. I have gathered these stencils up over the years, mostly from public domain sites, but do not use them to for anything commercial, unless you can find the original and its owner and assure yourself of it's bona fides. If you google public domain stencils, you will find oodles of potential or you can draw and print your own.
Point to note, I use a Black Sharpie (specific brand name), usually available from your local stationary shop, because I know it is colour fast and will not bleed. (Use it instead of the laundry pen, that is are a total rip off at double the price). Other standard colour Sharpies bleed. I know there are a lot of lovely colours, but believe me they are permanent, but bleed when washed. Sharpie have a newish product out, called stained??? I think that's the name! I haven't used them so I can't comment on how they work, but I understand they are permanent and bleed free.
A black Sharpie is about $2.90 NZ, less if you get a double packet. One sharpie will do about three stencils with a lot of colour blocking.
You can use fabric paint, to colour as well, little messier.
Hope you try this