Listen to music. Inappropriately happy music. If you can't stomach it, at least listen to something that isn't too "hardcore". If you can make Slender Man seem ridiculous to you, and stay calm or even laugh in his presence, then you have beaten his fear-inducing magic.
Learn to multitask for everything. A mind with more than one train of thought is a very easy platform to resist his mental magic. From what I understand of this (mostly conjecture), most mind-mages can only alter one thought processor at a time, making a person with more than one able to easily re-assert their natural mind over the magic it is exposed to. One can manage to "create" another train of thought, to run simultaneously with the first, through forcing themselves to multitask during every daily task. Don't just eat breakfast; read a book or watch TV too. Don't just write an essay; listen to music while writing, and leave the TV on in the background. Hyping up on caffeine can help with the training, but then you'll need to either wean yourself off of the caffeine or have a good supply of it.
From what I have seen and heard, a few of Slender Man's powers may just be him exercising his mind magic to induce fear. The tendrils sprouting from his back may not actually be there, really; it might just be a hallucinatory manifestation of the fear he is inspiring in you. The hive-mind that he uses to manipulate the Slender-proxies is the one of the simplest ways of using mental magic; complete domination of those with a weaker will.
Humans fear what they don't understand. The limb-extending, the tendrils, the lack of a face; all are causing fear because we can't identify how he does them. He doesn't; he has a face. One can see an impression of his face if they have a strong enough will.
In addition, I've been studying all of the forms of magic for a long time. A few of my ancestors did, too, from what I can glean from their flesh memories. Magic is an exercise of extreme willpower and focus, even more than it takes to resist basic mind magic, but it also requires a... well, I don't know how to describe it. It is like a spark of existing power within you; it can be hereditary, but it is often random.
Search for your magic while you sleep. Enter with a mantra, something along the lines of "power", "strength", or "ability", to help you find it. You'll know if you have it, but you won't if you don't.
On that rather confusing note, I'll leave to continue my research into Slender Man's weaknesses.
Remember: Knowledge is Power.
In addition, I've been studying all of the forms of magic for a long time. A few of my ancestors did, too, from what I can glean from their flesh memories. Magic is an exercise of extreme willpower and focus, even more than it takes to resist basic mind magic, but it also requires a... well, I don't know how to describe it. It is like a spark of existing power within you; it can be hereditary, but it is often random.
Search for your magic while you sleep. Enter with a mantra, something along the lines of "power", "strength", or "ability", to help you find it. You'll know if you have it, but you won't if you don't.
On that rather confusing note, I'll leave to continue my research into Slender Man's weaknesses.
Remember: Knowledge is Power.