Micro PK
The act of affecting Psychokinesis on a "micro" level, such as with probabilities, outcomes, random number generators etc..
It's been said that this can even effect things such as the outcome of a roll of a die. I find that this is something rather fun to play with, and not so hard to find some success in.
My preferred tool to practice this with - video games. That's right, video games.
I discovered this through Pokemon. People here know Pokemon, right? Know that confuse status? It has a 50/50 chance of causing a Pokemon to attack itself, instead of allowing it to successfully complete an action. Try confusing an enemy and willing them to fail each turn. Or if your pokemon gets confused, try wiling it to succeed. Same goes for landing such moves...a lot of moves that cause things like sleep, confusion, poison, etc depend on a probability factor, rather than the power of whatever character is employing it. Or attacks with low accuracy. Try willing that confusion/sleep to "land a hit".
Not a fan of pokemon, or have a game handy?
Try something else that works along the same lines...though I must admit it's quite exhilarating to psychically impact a game and know you're winning due to your own mental effort, haha