The best way to do so is to go to Delaware and register a company as an LLC (Limited Liability corporation), apply got a Tax Identification number and open up a bank account against it. That's all you need to legally work in United States if you do not hold a green card or citizenship from the United States.

Hi,
Depending on the country you refer to as abroad, for Canada and The United Kingdom you'd need to achieve at least overall 7 bands out of 9 in IELTS, whereas, for Australia, New Zealand and The United States of America, you'd need overall 89+ score out of 120 for TOEFL.

Best Regards