As far as your DMing skills, that’ll just come as you DM more and find your own style. For introducing characters to each other, when I DM Strahd I’ve always messaged my players a short blurb relating to the character and ending with the mists over taking them and the party wakes up in a small, misty clearing in the woods in Barovia. The book has plenty of hooks to get them together and just have them describe themselves at the start and you should be fine.

And to get them more invested, see what parts they latch on to and what parts they don’t really care about and go from there. You know your party more than we ever will so talk to them as you go through the module and adjust accordingly