I have emigrated to the USA twice, but now back in the UK.
The easiest way to move to the US is to marry a US citizen - not a choice that everyone has.
Then there moving there as a student...
Or for work - if you have skills that are highly sought after in the US, and you can find someone to hire you.
Or a work transfer, if your current employer has a facility in the US and you can transfer there either as management or a key worker.
Or as an investor - if you have money to put down to open a business and you employ US citizens.
Your sister cannot sponsor you until she is a US citizen (she can apply 5 years after getting her green card and processing takes about a year), and then you'd have about a 10 year wait to be called up for a visa interview.
Look at the US Embassy website (the visa section, both immigrant and non-immigrant - and then forget about the whole thing. But enjoy your holidays there .
If you like the North American lifestyle, Canada's a bit easier to get into - but you still need to be highly skilled.