A green card is a portal to the United States. It allows you to live in the country and in most regards act as a regular US citizen. Maintaining your green card can even open up the possibilities of becoming a US citizen.
Research the US job market for careers which are in need of more workers. US companies will not bring you overseas if they can easily fill their vacancies with US citizens.
Start getting an education focused on a promising career. You can either receive your education in you own country or apply to become a student in the US. If you can afford it becoming a US citizen has benefits. It will be easier to connect with companies to sponsor your green card and many US employers prefer seeing an education that is at least partially in their country.
Try to get internships and work experience in the field you are studying to make you a more attractive candidate for a green card.
Once you get a job in the US be the best employee you can be. Always come to work on time, and work hard on any projects. If you do this your employer will want to keep you around. I hope this advice helps you get a green card!