another way to think about it is:
for both sets of gears, easier (downshifting) is moving the chain closer to the frame of the bike. harder (upshifting) is moving the chain outward, away from the bike.
you can also think of shifting the front gears (or "chainrings" or just "rings") as the "main" shift: going uphill? downshift. Going downhill or settling into fast cruising? upshift.
the rear gears can be thought of as "fine tuning" to spin the most efficient or just "natural-feeling" cadence within the gear you've selected up front.
Once you're used to it, it will be more intuitive, you'll predict your next shifts without considering what I wrote. but until then it will help in understanding and deciding how to shift.