tl;dr: it went ok
The long version, pre game: I love trying new types of games . Usually there's little "at stake" for me personally. When there is, I handle my pre-game jitters by metagaming, obsessive prep (usually somewhat tangential to what the game needs) and if possible fussing with costuming and/or gear.
Which brings us to this weekend. My wife is running a campaign using the Firefly RPG books by Margaret Weis and team. Valerie has played and led RPGs for decades and has a preferred approach (I'll invite her to explain it at some point) and has hand picked the people playing. (And we purchased and then assembled a lovely table for it and I've vacuumed the living room and borrowed some chairs and prepared snacks.)
I have years of LARPG experience (not the same as being good, but I know what to expect) but this is my first tabletop RPG. Parts of the character creation meeting felt like when the adults speak in an old Peanuts cartoon: people said things but I heard only static. Afterwards I had to ask Valerie for a tutorial.
My biggest fear was the dice. I didn't know what to do with them, and when I roll dice usually everyone has to look under the table immediately afterwards.
So in my mini-tutorial I learned that in this game system, things relating to your character's "attributes, skills and distinctions" determine how many of each type of die you get to roll, and then you add up the highest scoring N dice, and any roll of 1 is a jinx, and sometimes you can add more dice after the initial roll and ... I'm going to have to lean on my team-mates just as I did during character creation. (They gave awesome advice, for example, "This option would be fun." I tried to pick options that would make me useful, since I have no preferences yet  and just want to survive and avoid embarrassing my wife.)
So, my coping mechanisms. Metagaming wasn't helpful  but I had a gear thing I could do: buy my own dice, and a tray to throw them in. I got three "sets" of D&D dice at The Game Lodge, set aside everything higher than d12, then I went to Guardian Games, which sells individual dice, and bought a few more of the popular weights that sort of visually went with the sets but sort of didn't, so my dice wouldn't have that absolutely-brand-new look. (Yes they are the color of my Ingress team. Might as well be consistent.) 
And then I had to learn the differences between each kind ... which the others seem to know instinctively after years of rolling them. And practice tipping them out of my hand without throwing them too hard.
Here's the tray that I'm going to throw the dice in , with all the dice turned so that the highest values are on top except the d10s, which have the 8s on top even though the 0s should be on top. The little pyramids are the d4s ... you read the number off the point. Yes, I didn't know this stuff until this week.
And for my obsessive (somewhat tangential to what the game actually needs but comforting) prep, I wrote down a few Chinese phrases as used in the TV series, although I didn't get far with that because I had brownies in the oven.
I'll write more after the game. For now, wish me luck!
Written the day after the game: I survived!
Val says she's a player centered GM and tries to let everyone show their strengths, or it could have been happenstance, but my first dice roll occurred when I was strolling up and down keeping watch while a much scarier character was cutting through a fence. My job was to talk to a guy who walked by and distract him if possible: one of my LARPG skills, except it was both role-played and scored with dice.
Let the record show that my first RPG roll was a d10 (Social attribute) + d10 (Influence skill) + d6 (specialty "at Borders" because we were at a port), and with those three dice I rolled 10+7+1. The top two equalled 17, more than enough to grab the attention of the NPC walking by (who had rolled low) and prevent him from noticing the fence damage, but the "1" led me got me a jinx of "attracting more attention" than I want. (Effect: anyone playing against me is entitled to roll an additional d6 to reflect that, until I can resolve the complication. In story terms, Federico invited me to apply for a job on his ship, the Astaire - yes the GM pulled these names out of her head - and I schmoozed with him and gave him my contact details, and he's going to wonder why I'm not interested or ... who knows?)
I was unable to "recover" from this complication at the end of the night and so I'm the only player that has one going into the next round ("episode"). Valerie is going to give Federico a full character sheet now, she says gleefully.
Thank you, everyone! See you in episode 2!
 How much I enjoy a game is orthogonal to how well I play it. Sometimes it takes a long time for me to start to play well (see: Ingress) and I measure progress in competing with myself.
 The others asked me whether I wanted to be the ship's pilot, and this might have been because it's a Firefly universe RPG and I was wearing a Hawaiian shirt. I wear them most of the time when I'm not working (and even sometimes when I am), so it wasn't on purpose. As I recall it was the shirt in this Ingress related photo - thanks Agent a2kdh2k for the picture. Danna and Tony and I were delivering bottled water and cell phone cooling packs to groups of ENL players downtown.
 As just one example, in LARPGs I would try to figure out how well players knew the GMs in real life and/or what their reputation in our gaming community was, as a way to try to figure out whether their characters might have hidden depths. On one memorable occasion my noticing "our team has more powerful players than it ought to have" gave me advance warning of shenanigans, and following the advice "write what you know" I wrote a screenplay about a chronic metagamer.
But in this case I am the one dating the GM and it wasn't doing me any good because she is being careful not to give me extra information because that would take the fun out of it.
 "My game store" when I first moved to Portland was Bridgetown Hobbies on Sandy; I always try to find a store with miniatures and model painting even though I don't indulge myself, one that stocks all the flavors of Fluxx and is near my home. That retail space is a marijuana store now, but I think it's still an Ingress portal. The Game Stop is the indie game store closest to our present lodgings and we're planning to attend some of their events: 85% of the floor space is play area!
Yes, the phrase "present lodgings" echoes the line from Pale Fire: “There is a very loud amusement park right in front of my present lodgings.” Our version of the amusement park is that we live on a smallish elevated triangle of land formed by the intersection of two highways near a cluster of conjoined strip malls, anchored by a Jo-Ann craft store and the amazing Joy Cinema, with amazing international food options amidst the clutter. In a separate post I will explain about how the Jo-Ann's warehouse just across the street disturbs my dreams.
And in a deeper sense the troubling amusement park is the U S of America, and that's really a separate post.
 Valerie looked askance at the tray, but it did the job: kept my dice from rolling away from me, and also when I needed help I could lift the tray up with the dice in it and show it to others. Eventually I hope I'll feel more comfortable and be able to promote it to a tray to put earrings in.