visas are the main thing that will dictate this:
You can go on a family visa if you get married to an American Citizen
You can go on a business visa if you bring $500,000 or $1m to the economy (depending on type of area)
You can go on an employers' visa if you are hired by an american company.
Then there are a few other types of visas for things like trafficking victims, the "lottery" visa, asylum seekers, iraqis who assisted the US, etc.
As an 18 year old, unless you have considerable wealth to begin with, your best chance of moving to America is by an employment visa. America is a big place, with lots of different cultures and areas. Think about where you want to be living and what kind of community you want to live in.
It sounds like you have the rose-tinted idea of "moving to america", before actually properly weighing up and planning the best routes.
American lifestyles offer lives from corporate zombies, tech startups, all the way to off-grid survivalists and everything inbetween. No matter what you choose, you can be pretty sure that 99% of them will be different to your expectations.