Social transition refers a number of changes that can be made in a trans person's social life and situation, including:
If a person that you know begins to transition socially, it may be necessary for you to actively change your behavior, or to help bring about changes that will ensure the person's comfort in their new gender role. These can be downright difficult; switching pronouns, for example, is often not an intuitive change.
Some appropriate ways to aid friends and family through social transitions:
First: while a new name and pronouns can be a challenge for everyone, it's very important that you try your best in this area. Don't beat yourself up overmuch over slip-ups, but do remember this: if you're a woman, you'd probably be downright offended if someone called you "he." Trans people have experienced this discomfort daily, and often for many years; it is a constant sharp edge that drags on the ends of conversations, and though they are more accustomed to it than you are, it is nonetheless a basic courtesy to use the language that better suits their identities.
Second: if someone begins to dress differently from how they used to, this may seem a shock, and your level of ease around that person may decrease sharply. If your initial response is to say "You look terrible!" or "But that boy isn't who she really is!", please try to hold off on that impulse for a while! Write it down, and return to it later with a clear head and a rested eye. You'll generally find that this feeling is based on an initial jolt of fear, which ebbs as you grow more understanding of the person's sense of self.
Third: Begin — and you can go about this a little slowly, if necessary — to learn to see and treat this person, in your mind's eye and your emotional knowledge, as a member of their preferred gender. This doesn't mean falling back on simple sterotypes (e.g. I shouldn't open the door for him, since he's a man now); I'm instead referring to a subtle shift in world-view, one which colors your social interactions with everyone. Just: this is what the person is. Really. Yes. Just dwell on that a while, even if on the back burner, so that it sinks in and becomes more natural for you.
Finally, one last note: you may notice that, in the link that led you here, I referred to social transition as sometimes being called "Real Life Experience." Real Life Experience is part of a set of medical guidelines — called the Harry Benjamin Standards of Care — that are sometimes used in the treatment of transitioning people. Some folks use the terms "Real Life Experience" and "social transition" roughly interchangeably, with the following differences distinguishing them:
When people have, according to their personal standards, made a full social transition in every aspect of their lives — those people are then described as living fulltime.