A fun way to write a letter, is using a notebook. But all those blank pages can be a bit intimidating and demotivating. How on earth are you going to fill all those? Maybe, like me, you don't always have that much to tell. You can of course tear out a few pages here and there, but chances are, the notebook will fall apart. What you can also do it fill a bunch of pages with fun pictures, drawings and collages. Here are a few examples:
You can do this before you start writing, but it's more convenient to do it afterwards. Just leave pages blank while you're writing. This way you won't have not enough or too much pages when writing. Also: if you're going to doodle, make sure you use a pen that doesn't bleed through the page, as you can see I didn't. This will make reading the writing more difficult.
Notebooks with a boring cover are cheaper, but that's ok, just cover it yourself! Here's what I did with mine: