Yes you can. I'd say that over half of magic is fueled by the belief of the castor and so if the castor believes that writing any specific thing will aid or even cast a spell then it's a perfectly reasonable assumption that the spell possess as much potential to work as well as any form of long or complex ritual.
Everything is possible,if you use your strong will and intention. Just be careful what are you wishing for..some even ex Fluff after many years end up in mental hospitals for being a Bonopart,mermaids,vampires. Lol Universe even blessing Fluffs too
k, i'll go with a really old one, the abracadabra spell. on a piece of paper you write abracadabra, taking away one letter each time, until all the letters is gone and it forma a triangle. this is an old way of combating the common cold. personally i've never tried it, but it's claimed to work weaken a cold. how this works is you transfer your energy into the words, visualize yourself [or friend] getting better. all spells work the same, how well you can focus and charge an object will increase it's ability to work.
you do have a point though, it is hard to believe writing something on paper would do anything, but it can. a spell is nothing more and charging an object to help you achieve a goal. a spell could be simple like washing your floors while saying a protection chant, or as complex as casting the same spell for a month straight. whatever feels right to you is the best spell to do. personally, i study potions for that reason, and am trying to learn more about herbs, but i have trouble remembering them all lol.
I must point out that all this believing is worth nothing if what you're believing in isn't real. The specific topic of this thread is quite possible, but the idea that "everything is possible" or that belief somehow equates to possibility is simply untrue.