Are there proper steps for going glitch-hunting? This question just pops out of my mind since I'm really curious about how people find insane glitches. I know that a lot of glitches were founded by accident but how do glitch-hunters prepare themselves for glitch-hunting.

Every game has it's own way to find a glitch. Basically, it's "play the game in a wrong way" sense of things. For starter, you can just do a bunch of output on a set of game area just to find an anomaly from it, resulting a glitch or even a softlock. You can also do a "code reading" by checking the game source code, but then again that's tedious yet rewarding.

For example, in a game that i moderate (Grimm's Hollow; it's an RPGMaker game), we do a glitch-hunting by testing a bunch of way to interact with an entity / sprite / gameplay. In recent findings, we found out that we can go out of bounds by doing a menu input while in middle of a jump animation, which saves a lot of time than we were expected.