One tool that is helpful with any D&D group is a sort of starting ritual, ice breaker, or some type of thing to get the group in the mood. In college, I had a group that would watch The Gamers, an hour long indie film about a D&D group, as people were coming in and getting set up/finishing their food, other groups, it's the background music starting to get into the zone, and in nearly all groups, a brief recap is key. However, one tool that I've been using recently that I really like is the warm up question- that is, a question asked by the DM to the players about the characters before the game begins. This both acts as a starting ritual to indicate that the game is beginning, and a chance for the players to start thinking about their PCs, and from my experience, they fall into four categories- Therapeutic questions, foreshadowing questions, ice breakers, and world/character building questions.
The therapeutic questions I've seen asked by the various therapeutic DMs in my circles. As I'm not a therapist, I generally don't use them, but they tend to be more oriented towards helping kids identify their coping skills, strengths, and things like that. (As an aside, please don’t do any therapeutic work unless you are a licensed therapist.) Examples might be:
“What is something your character does when they're anxious? Are you the same way?”
“What would your character say to someone who is dealing with loss?”
“What is something you like about your character that you wish you could embody?”
Foreshadowing questions get the player thinking about their role in the upcoming session. Sometimes there might be a tough decision coming, so getting the players thinking about that ahead of time without spoiling too much can pre-load those decisions. I do a lot of these later in the campaigns, as they fit in well and help save time. Examples include:
“What job would your character want in a castle?”
“Does your character prefer working with the law, or doing their own thing?”
“Is your character more likely to prefer the safe route, or take more risks for greater reward?”
Then there are fun ice breakers, which are often just a good way to build up relationships and group chemistry. I really enjoy doing these earlier in the campaign, as they help everyone get into the game.
“In character, ask another PC a question. That PC's player has to answer in question.”
“As your character, describe yourself (the player).”
“What alignment does your character consider themselves to be?”
“If your character could create a PC, what would they be?”
Finally, there are world building questions, which are oriented towards developing the characters. These are good for when you can't think of anything else, as they're fun and easy, but also can be used to give the DM material. Examples include:
“What is your character's greatest achievement?”
“What is something your character thinks about a lot?”
“If your character could retire with a big pile of gold, what would they do?”
“Tell me briefly about your character's family.”
That pretty much sums the four categories of warm up questions I've utilized in my groups, but I'd love to hear which ones you use, or if you use other starting rituals for your games!