From a quick glance....and in B&W so you are challenging yourself!
Good luck.
1) Looks like the kind of comic you create when you really want to illustrate a situation or feeling. You are doing a good job of establishing the frustration of a picked on kid- about to (probably) get his revenge and set things straight!
2) The hero has a similar haircut to the main, blonde villain. I think the headband works to differentiate between the two, but sometimes I'm not sure who is speaking until I read what's being said and figure it out.
a) I suggest you draw the headband fully so it's real obvious a character is wearing one.
b) The bad guys or all characters (should) have VERY DIFFERENT HAIRCUTS and outfits
- the teacher is bald.
- the bully has SPIKED hair
- A girl has long black STRAIGHT hair.
- A character has SHORT PUFFY hair
- Hair that curls on the tips.
- long sleeves versus short sleeves.
- t-shirt versus jacket
- long pants against shorts
- a sports jersey with numbers on it is easy to remember
- the rounded edges of a sweatsuit is easy to contrast against sharp slacks and button-down shirts.
- a teacher or principal is BALD on the TOP, but has hair on the sides.
* you're doing pretty good in that department, so far.
3) Writing, I would use this site https://www.rhymezone.com/
to find synonyms so that people are saying the same thing using different words.
Idiot - dummy - jerk - fool -etc
4) FONTS - I would pick a different font. You're drawing style is very loose and expressive. I think you need a more human writing font to match.
On this page I like SKINNY
On this page I like indie flower and shadows into light and Nanum pen script and, and too many choices to name - you get the idea.
5) World building - that bad student is able to just punch a teacher in face like nothing? I get that he's bad, but damn, what a first day at school. lol Maybe that guy needs a day to show how bad he is- and slowly getting worse. I mean, how does he do this every day and stay in school? Like, no adults are going do something so Dan has to get his superpowers first?
I think the most serious bullying should be outside of class/school so that very few people are aware. Like he gets jumped after school. And something happens during recess or on the walk home - or in Gym class.
There's a huge amount of opportunities to bully- outside the classroom/school.
6) Characters - I think we needed Dan at breakfast since you started with him waking up. You could have started with him in class (or at the bus stop) since waking up didn't tell us anything. Show his useless parents- oblivious to his problems or that they don't really care and think it's normal. Maybe he's got a single mom or/and the stepdad is a jerk and HE was a bully too so he takes the bullies' side. Or he thinks Dan should just toughen up and deal with it. AND it helps to make the bullies more of a gang so that Dan has a few kids to deal with. One jerk aint so bad, but a bunch can be scary.
7) Inspiration and Execution - you use curse words so I assume you're an adult. Take a look at this movie (it's rated R I think) And maybe you can see something in this.
The overall idea, is a known one, but worth retelling your way, so maybe this movie might spark some ideas.
Good luck and let's see what happens next.