This looks like it might be a duplicate question that's already been answered here, as Macaco Branco mentioned in the comments. But I did want to give a unique perspective on this, as someone who was once bullied as a child myself.
I'm going to assume you're in school still, and that you're a boy. Hopefully that assumption isn't wrong. My advice would still generally apply if you were a girl or an adult, too.
The obvious answers are stuff you already know: Avoid the bullies, keep your head down, don't provoke anyone, and try to blend in and not stand out. Beyond that, get stronger and take MMA, BJJ, or Muay Thai.
But honestly, do you want to know the thing that has the greatest chance of actually working? Something that will sort of immunize you from ever being targeted by a bully again?
The answer is: Make friends. As many as you can. The more the better!
Bullies pick on people who are easy targets. Those would be people who stand out and who don't have lots of friends, or no friends at all. They don't pick on the popular kids. They don't pick on the jocks. They don't pick on kids who look normal, act normal, talk normal, dress normal, and have normal interests.
Now, to some degree it has nothing to do with looking and acting like everyone else. It's all about making friends. Making friends often means not being weird and not being the sort of kid nobody wants to be seen with. Those kids simply lack friends because they're different. Not a lot of kids are going to accept kids that are unusual. So those kids who are different will often struggle to make friends.
And the more a kid goes through life feeling different and acting different, the more likely that kid is to be introverted and therefore only need one or two good friends. Those kids with one or two friends are targets for bullies. Chances are, their friends are also like them, weird and different. Bullies won't be deterred by those one or two friends of theirs.
So, I know it's unfair. I know you're probably different from others. You stand out in some way. Maybe you're weaker physically. Maybe you look younger than the rest of the kids in your class. Or you wear feminine clothing, or clothing that's really colorful when the other boys don't. Maybe you color your hair. Or you wear earrings. Maybe you listen to music that nobody else does, and you're not afraid to show it by wearing that band's t-shirt. Or you have interests that are uncommon that nobody else can relate to. Etc.
All of those things are the way you express your individuality. Or they're not an expression, it's just who you are. And it's not fair to ask that you change just to satisfy a bully.
But I think that's the wrong way to look at it. I would reframe that in your mind a bit. Instead of changing to satisfy someone else, think about wanting to do whatever you can to make new friends and be the sort of person who everyone wants to be around. Do it not to satisfy others but because you personally want to be someone who everyone likes. That goes beyond what you wear and what you look like. It's also and mostly about being friendly and warm, and taking a genuine interest in and appreciating others, who they are, what they're into, as well as their problems in life. And not judging them for it.
And I want to be clear here. It doesn't mean changing who you are and your interests. It does mean that you will be less concerned with conveying to others who you are and, rather, shifting the focus onto them and discovering who they are, their uniqueness, their interests, and so on. It's less about you and more about them. Let them shine. Let them do the talking. Let them tell you all about their favorite subject: themselves. And listen to them, really listen.
The worst thing you can do is put up some kind of barrier that prevents them from opening up to you or getting closer to you. You need to be better about gauging their reactions to you. If you're wearing a t-shirt that offends them, for example, maybe you should stop wearing those t-shirts or tone that down a bit. That's less about you repressing your individuality and more about caring about others around you. That's it.
And you might be very passionate about some subject and can talk for hours about it, but know that most people get bored beyond a few sentences. Keep it short and only give them more if they ask you for it. The more time you're spending talking, the less you're able to find out about them, and the less they want to be with you.
You don't want to anger them if they believe something that's against what you believe. So just keep those things to yourself. You don't want to make them feel less than you in any way, so stop trying to play yourself up. You don't want to make them feel awkward around you, so don't do or say stuff that other kids aren't doing or saying.
Instead, make it so that they feel like they can really open up and tell you their interests. That should be your focus. Take the focus away from you and put it on them. It's not about you trying to be someone you're not. It's about you trying to put the focus onto them.
School can be brutal. I remember trying to make friends with kids that seemed like they could use a friend. I figured we were in the same boat, so the more the merrier, right? And I would try to befriend them, only for them to lash out at me and push me away. They didn't want me near them, either.
There's a reason why those kids are alone. They're not friendly, not nice, and they don't put in the effort to make friends. Many also have mental or personality problems, unfortunately, and push people away. Other kids see them alone and know not to approach. Like I said, it's brutal sometimes.
So I'll just say you have to break out of that. Start making new friends. Easier said than done. Chances are you don't know how to do that. That's great! Be aware of that fact. That will lead you to asking the right questions. There are books on how to make friends. Search for them and read some of them. Take from them what you think you can apply. And then little by little, make changes in your behavior that increase the chances of you making new friends.
Don't worry if you're not successful right away. It can take a whole year or even longer before people start coming around, and you get in with the right social circle. Acting all friendly all of the sudden makes other kids suspicious. It takes time before they get used to the new you and begin to accept you into their friend groups. Then once you're in one group, it becomes easier to branch out to others.
For you even, it's going to seem like trying to be someone you're not, at least at first. When you're far enough along in this process, I'm just gonna tell you that you won't have to worry about that anymore, because it will be genuine. That will be who you genuinely are. It won't be an act. And kids will feel that and will begin to trust you.
By the time you find yourself in a larger social circle, you'll have forgotten about that bully. The bullies will simply vanish, because you're no longer a target. You have friends. And if you do still get bullied, your new friends won't stand for it. They'll push back on the bully for you. That's what bullies fear the most. Bullies don't want to be the ones who are ostracized by the group, because that would make them just like the ones they bully.
Whatever you do, don't become violent. Just channel all of that emotion into motivation for becoming the one everyone wants to be with. That's your goal. And do reach out to adults that can help if it becomes too much to handle.
This is my perspective. I hope it helps. Good luck.