My reply to would-be Americans is "Be the best you can be in whatever you choose to do. Right now." Then, visas, opportunities, and the rest of good things will come soon.
Way too many people think that opportunities wait for them at destination X. Think about it! Does it ever happen to anyone? You create your own path right where you are. That path will then lead you to your destiny. Do dream possible dreams.
Let me bring up an example. I used to ride taxicabs a lot because of my work in Washington, D.C., a decade ago; I also talked to taxi drivers. About 99.99% of cab drivers were foreign born. Half of them had professional careers in their native countries. There were a few doctors and engineers in between. What I want to say here is that it's likely that you may not do the same jobs with prestige and professional respect like in your own countries. It's too bad for the wasted professional expertise from foreign countries that does not get proper use in chosen career fields in the U.S.
On the other hand, even if you're just a lowly toilet cleaner or street sweeper in your country, do it so well that people will start talking about how clean you take care of the toilets or streets.
I just finished reading a couple of books about Bikram Choudhury. He was a poor boy from South India. Mr. Choudhury is the master of his knowledge and professional field as Yogi. As you know you normally don't become a billionaire and famous as a fitness and spiritual guru. Decades ago, a U.S. president offered him a visa to come to America because Mr. Choudhury did his job so expertly to cure some illness of that president. Yes, with Yoga! He now has professional recognition not only in the United States, but also worldwide. He also becomes very wealthy living in one of the most affluent neighborhoods in Beverly Hills, California; he passionately talks about his expensive Bentley cars in one of his books. This is an extremely rare case that's difficult to replicate though.
So you should learn about your own talents and develop them to fullest potential. I knew a handful of local staff who worked at American embassies in foreign countries. They were regular office workers by profession but highly respected and recognized by their American bosses because they did their work extremely well. Just before their retirements, these local employees were able to receive special visas to immigrate legally to the U.S. You know that when they come to the U.S., they will continue to do the same excellent jobs.
Then, you have to learn "To Give and To Receive graciously." Think about what you can contribute to your community professionally or personally. And contribute your talents to the best of your ability. Americans do resent anyone who comes to America to take advantage of their vast richness. You will feel the same way if an American or anyone becomes a parasite on your native land's resources. I cannot promise what you'll get back for giving. But a miracle and happiness will happen to you.