1
Know you're unique. For starters, know that you're already different than everyone on the planet. Sure, some people are more different than others, but all of us have a unique set of experiences and characteristics that spell out a different reality than everyone else on Earth. No one else has the same brain you do, the same thoughts you do, and the same reactions as you do. You're different by just being human.
Labels are pretty useless. Even striving to be different isn't something that's truly achievable. A quick change of cultures will show you that people operate differently by default. Instead, accept that you're already unique and work with yourself. Who is you, anyway?
2
Find yourself and be yourself. In order to be as different as possible, you have to be you -- not a carbon copy of someone else. If you don't know who you are, that process can seem a bit scary. In order to be yourself, you have to find yourself. Do you know what it is you like? What you are like? Who are you when no one else is around?
It's important to love yourself, too. If you're not comfortable with who you are, you'll inevitably end up trying to be someone else -- or at the very least being someone who you're not to please others.
3
Spend some time alone. It's normal nowadays to be constantly bombarded with stimuli -- whether it's on a screen or the people around us. To really get down to who you are and what makes you different, spend some time alone. Disconnect from everything. What are you left with? Meditate on what matters to you.
We're constantly being told what to wear, what to eat, what to say, what to look like, how to act, what to read, what to watch...you get it. Get alone and all of a sudden you'll be without guidance. It'll be a strange feeling, sitting there, thinking about what you wouldn't miss if you never had to wear/eat/say/do/read/watch it again. Think about what aspects of your environment are shoved onto you and which ones you openly embrace
4
Know what you want. Be very careful that you actually want to be different. Maybe you're just in a group of friends that you don't jive with and that little voice in your head is just being misinterpreted. What does different actually mean to you?
What do you perceive as normal? What is it about people that strikes you as "the same?" Every person's interpretation of what "different" actual is is, well, different. Is it how they look? Act? Talk? Dream?
5
Know how you want to be different. Once you've pinpointed what "different" is to you, how do you want to go about it? If you're in a group of friends that only eats Swedish protein bars and wears pink on Wednesdays, how do you want to go off on your own? Do you want to become a math mastermind or do you just want to shake it up by wearing purple? You could be different in so many ways.