Travelers can get a free first-class seat upgrade on domestic flights if they hold AAdvantage elite status. Moreover, non-status travelers can upgrade their seats in American Airlines First Class by using Instant Upgrades through AAdvantage miles and cash, and ask for paid upgrades at the ticket counter for last-minute upgrades. Travelers need to avoid basic economy tickets because these are not eligible for any upgrades. For further information, travelers can also visit the official website or read the blog mentioned by Fares First Class