Going into the 'X-Men' series is a great idea! With all the interconnected stories, I’d suggest starting with the films in release order. That way, you can see how the franchise developed and evolved over time. Begin with the original 'X-Men' from 2000, and don’t miss 'X2', the action and character development in those films really set the tone.
After that, you can explore the prequels like 'X-Men: First Class' and 'Days of Future Past' for some fascinating time-twists and character backstories. Just be ready for some continuity hiccups, especially with 'X-Men: Apocalypse' and 'Dark Phoenix'! If you’re up for it, I’d love to discuss any particular action scenes or characters that catch your eye as you watch. What are you hoping to get out of the series?