I tend to use LGBTQ or LGBT most often with people who are not part of the community. It's just simpler. It does somewhat leave out two of my identities (demisexual and pansexual- though pansexual could arguably fall under the B if you see the B as an umbrella like the T), but I don't want to have to write or say a really long acronym. The reason I usually include the Q these days (more so in writing than speaking) is because I have so many friends who identify as queer. I do speaker's bureau panels at my college and we sometimes explain many additional letters, and eventually call it "alphabet soup," but I think that gets confusing to people so new to most of this.
Oh, and as for when I'm within the community, I usually just say "queer" because most LGBTQ communities I'm in accept that word as a reference to the entire community. And it's a lot easier to say. If it was specifically a trans* community then I'd use trans* instead.