Latch and lock all windows and doors. Keep an eye out for levers and handles as cats can use their paws to push those down. Lock them or add in extra security like a door latch or hook and eye.
We live in the tropics, so we love airflow. You'll have to add netting to windows and maybe doors.
Consider that cats combine the skills of a champion rock-climber with the flexibility of an Olympic gymnast. If it can be scaled, they'll do it. Just because it's there.
And should they need to jump or wriggle through a tight gap, they'll activate an inner boneless button and stretch impossible lengths.
If you use security grills or covers for windows and door, make sure it's a tight fit. Leave no gaps, even at the very top of a tall door. Ensure it can't be bent or lifted.
Usually grills are made to prevent human entry, not to block an exiting kitty. Cover large grills with fine plastic chicken wire. Be sure to secure it with self-locking cable ties at intervals.
A bored pet is an escape artist. A happy distracted pet may try less. So offering entertainment is an excellent idea.
As cats love to climb, place perches or a cat tree next to the window. Like sailors, they will climb and perch, acting like miniature lookouts.