You realise you're in for a boatload of issues you never signed up for, but that doesn't mean you can ignore them.
Your racist monoracial relatives who don't approve of your parents' marriage or your mixed ethnicity, is one major one. You meet up once a year and never feel like you belong. You won't. And nobody will go out of their way to make you feel welcome. Everyone speaks in a language you don't understand and they're not gonna bother to translate for you - the perceived outsider.
You may have white privilege. You may even be white passing. This will gain you loads of attention, unwanted or not, at the expense of people who don't look like you who need the attention or deserve it better than you do. It's not my fault, you protest. Yeah, well, doesn't mean you shouldn't do anything about it either.
You're going to discover colourism. You're either going to be darker or lighter skinned than some of your family members. If you're lighter skinned, you'll enjoy more positive attention. If you're darker skinned... Well. We've heard all of those anti-black remarks from the people around us, and the advertisements on skin lightening... It won't be easy living in a world that demands that you hate yourself, hate your skin, hate your heritage. Us lighter skinned folk really need to speak out against comments on darker skin (God, the number of infuriating comments I've gotten from strangers about how fair I am and how that makes me so much prettier...) and remember that lighter skinned does not superiority make.
People are going to fetishise mixed race babies right in front of you and talk about you like you're an exotic hybrid. Tell them how gross that is. I always think of my monoracial friends touching my face gently and telling me how I'm lucky that I'm mixed and how that makes me better looking and I get so angry. Not at them, but for them. Just because we're mixed doesn't mean that we're the best of the worlds we've inherited. Doesn't mean we're any more talented, or intelligent, or better looking (the Ms Universe and white passing or Eurasian girls thing is a discussion for another day and involves eurocentric beauty standards so refer back to white passing privilege).
Some people might even argue about what culture you belong to. None of them and all of them, you think in your head. "You're only part x," your friends exclaim laughingly. You're part everything and wholly nothing, you inadvertently recall. Being everywhere, but belonging nowhere. You don't know the traditions, you don't remember practising any, your childhood is ethnically ambiguous. Let me tell you that you are more than the sum of your parts and that your inheritance of a culture does not come with the qualifier of having had to exercise it from childhood. You can choose to learn more about one of your cultures at adulthood and still belong to it. Likewise, you can feel completely disconnected to it and never have to identify with it if you choose not to.
Stupid xenophobic bullies will make their presence known. My sister was teased for years over her first name (Maria) and over the fact that our mother is from the Philippines. Some of her friends (whom my mother was friendly with and picked up from school and sent home, welcomed to our house, cooked for and listened to) made jokes about our mother being a maid, about my sister being a maid (not that there's nothing wrong with being a helper! There's so much we wouldn't get done without them.). They'd call her "Maria" like they would a dog. Feel free to tell these people off. They don't deserve your friendship if they don't understand why they're wrong after you've told them. It's okay, you'll always find better people.
Racism becomes a much more complicated issue when you're mixed race.
You're not going to know how to deal with a lot of the problems that do crop up. And that's okay. You will meet people who understand, or people who don't but are willing to listen. Find a supportive network, and support those multiracial children who are less privileged than you are. Educate the people around you on why and how they're being offensive.
I'm going to end this post here because it's past midnight and I can't think of anything more to add to it. Feel free to post comments on what I've missed. If I've overstepped myself, do correct me.