I get some last-minute party gigs around the holidays and they are delightful. I was very pleased when one of my regular customers asked to buy a reading for a friend as a holiday gift. I always have at least one deck of cards with me when I go out but I don't feel comfortable initiating the offer for readings at family/friends gatherings. My friends and family know I read and they also know I will read for them if they ask.
I don't want to make family and friends events "all about me" and my work with tarot. I want them to feel happy about celebrating the time together with me and not to feel they are always under a microscope. I like to share the time with them too.
When I get together with people, there are things I pick up without a reading. That's happened to me all my life though and like a lot of adult skills I've learned to keep that to myself unless and until they want to talk about that. Otherwise, I have a huge respect for people's privacy and a healthy respect for wiggle room in my own accuracy.
Usually I have a low-key deck with me, something that is light-hearted and non-threatening (unless of course the holiday demands something interesting like Halloween). This year, I'm hoping to have my own decks with me to read with because they are purposefully light-hearted without sacrificing meaning.
I don't recommend reading under the influence. OK, and here's a funny one for me personally: I don't like to read after I've had turkey because of the sleepy effect turkey has on me! That's just my own quirk.