Once you've become a permanent U.S. resident (green card holder) traveling abroad and returning to the U.S. becomes easy. Even so, there are rules you should be aware of, particularly if you might get stuck outside the United States.
When sponsoring a family member for U.S. immigration, you might need to file an I-864 Affidavit of Support to show that they won't become a public charge.
People immigrating to the U.S. through family or through an employer that's owned by family will have to show that the U.S. petitioner is willing and able to act as financial sponsor.