For first time watching I would say release order
Alien (1979)
Aliens (1986)
Predator (1987)
Predator 2 (1990)
Alien 3 (1992)
Alien Resurrection (1997)
Alien vs Predator (2004)
Aliens vs. Predator (2007)
Predators (2010)
Prometheus (2012)
Alien: Covenant (2017)
The Predator (2018)
Prey (2022)