Remember that most of us only show our good shots, not our failures.
We're all (hopefully) always learning.
It really does help a lot to learn your camera and to learn how it reacts in different situations. But this takes time, attention to detail, and - unfortunately - lots of mistakes along the way.
That way, for example, if you run up to a similar situation again, you know now that your camera will over expose the faces if you leave it in evaluative metering. So, you can either (a) keep it in evaluative, but turn down the EV by (just a guess) one stop; or (b) spot meter off one of the faces. Then, with the results you get from that session, take note of your results, and toss that into your bank of experiences.
Soon, and with enough attention to what worked and what didn't, you'll know what your camera will do in a wide variety of situations, and using the right settings will become 2nd nature.
For your landscape shots, it's very hard to expose a photo properly when part of the scene is in shade and part is a sunny sky. Maybe frame a shot so that the sky isn't included? Pointing the camera away from the sun should help, too. Again, trial and error, with some attention given to what works well and what doesn't, should prove useful.
Keep it up!