You don't need advanced tools like Photoshop to create a glitch effect, Paint can handle it with a bit of creativ ...

For precise painting around edges and corners, he says a blade paint brush is an excellent choice. "Its fine, wide tip is ...

For a different effect why not use a toothbrush? You can use this to sprinkle paint onto your painting. So I'm going to dab it here in the green paint… and then - this is a bit messy - sprinkle ...