Another fundamental part of the visa application stage is the review of your financial ability to start your life together in the US. A finding that one is likely to become a "public charge" (i.e. dependant upon government assistance) is also a ground of inadmissibility to the US. To prevent that, you need to submit Form I-864: the Affidavit of Support. The I-864 is used to establish two things: domicile of the person signing the form; and financial status for supporting the intending immigration.
Domicile is essentially a state of mind regarding intent; a US citizen who has been residing abroad may still be domiciled in the US if their intention is to return to the US. For the petitioner-sponsor, this means the intent to return to the US either prior to or with the sponsored immigrant
Financial status means confirming earnings of at least 125% of the Federal Poverty Guideline for a family of your size annually in the US or have assets in the US that are either 1. five times that figure-for non-spouse sponsors (if 125% for your family size is $25,000, your assets would have to equal $125,000); or 2. three times that figure for spouse sponsors ($25,000 would require $75,000 of assets). If you are not currently working in the US and/or you do not have sufficient assets, you can enlist a Joint Sponsor. The Joint Sponsor will also have to submit an Affidavit of Support showing that their income or assets satisfies the 125% level for their family size, plus the intending immigrant (100% for military families). To find the current 125% (or 100%) figure for your family size check out https://www.uscis.gov/i-864p .