Feedback? I'd say that you need to frame with a bit more top-space above the people when photographing a seated or standing full-lngth shot in a horizontal camera orientation; your displayed shots of the ladies and the young man in the snow feel a bit cramped, with their heads too close to the top of the frame.
As far as "natural" activities and posed or formal shots...it takes some experience, and you've already gotten in a few shoots, and have done okay. Allowing more space around the people is one option I think I'd immediately consider. As to the natural,genuine expressions you want: those expressions can often take 10 or 15 minutes, or maybe a bit more in terms of actual, real-time shooting, to come out of some people. Often times, people give what I call their "picture smile," for the first 10 to 15 minutes of a photo session. What I mean is tat at the start of a portrait session, many people, probably most people actually, well they project their practiced, life-long, "I am having a good time, this is how I always,always smile in a picture, dangit!" expression. SOME people never,ever get over this habit,and they project the same expression in photos, every single time. As in every, single photo. Teeth bared, smiling-in-name-only, their eyes belying nervousness or some other subtly negative emotion. But most people, after 10 to 15 minutes of showing their "picture-smile", begin to open up, to relax, to vary their expression.
It is the people photographer's job to elicit the desired expressions, and then to shoot photos of the expressions, and to help his subjects project the right type of expressions. Eliciting the desired expressions might involve coaching, describing, modeling and showing, and so on, what is desired. I think that pre-shot setup and pre-shot coaching, and describing the desired end photo and expression, and being encouraging, and then shooting plenty of frames and praising the subject's efforts, goes a long way. Do this on every pose, and shoot 15, 20 frames at least, of each of the desired, "final" poses. You need to describe the desired expression, and help the subject "play-act" in such a way that they feel FREE and encouraged,m to move away from that awful,awful "picture-smile" type of cheesy expression that most people use. Getting away from the "picture-smile" feeling can take 10,15,20 minutes for many people. Some people take longer.
The really genuine, amazing pictures often come about a half of an hour to 45 minutes into a real photo session. Unless the person is especially outgoing and pliable and malleable in his or her expressions, you're going to have to shoot and shoot and shoot, until the person loosens up. After an hour, or so, almost any non-model type subject is done for. Unless you shoot at least 30 minutes, or have a very developed way of photographing people, and can really,really "work people magic", your best bet would likely to tell people you'll shoot pictures for about one hour, and tell them,literally, "Not every shot's a winner, so there's no need to worry about every shot being perfect, and we do NOT want you to be smiling with a big and toothy grin in every single shot."You must prove that to them, by posing them, coaching them, encouraging them, and snapping plenty of photos, so that they can see for themselves that they do NOT have to project that same-old-same-old "picture smile", that you will snap them in different types of expressions.
Don't,don't,don't shoot ONLY smiley faces! That alone, shooting less-than-a-smile, demonstrates to real people that they do NOT have to be smiling, in order for you to shoot a photo! That is a message that needs to be understood, and many people do not think that way.
With nervous or less-than-great subjects, I think that a newcomer to posed people pictures should shoot 300 to 400 frames, at least, in an hour, if he or she wants to have 15 to 20 real,genuine,excellent frames at the end. Many regular,ordinary people are not all that great or all that comfortable in front of a camera. I'm describing a way that's worked for me when photographing nervous, sort of uptight people. To make a pizza, it takes time for the dough to rise.