What should I expect?
Any tips or tricks or advice for a newbie?
What was your own experience as a newbie? (Esp. if you, like me, are going in not already in great shape)
What, if anything, can I do at home over the next couple weeks to best prepare for getting started in a box?
The main thing is definitely the disclaimer that heatseeker threw out there. Everything will depend on the box. Also this: you will most definitely be extremely sore. For me, I am very delayed onset, and almost always feel the worst of it 48 hours later. I know some people that feel the worst 24 hours later. Most gyms (boxes, whatev... I know some that hate either/or term) have a type of foundations class where they guide you through all of the lifts that you will be doing. Be extremely attentive during this time and ask questions if you need too. This is where the coaches need to be talking a lot to you and helping you out.
Tips/tricks/advice for everyone, not just newbies, check your ego at the door. If a movement is too hard, ask for scaling optionis. I hear so often, "Oh, but I've heard so many people get injured in Crossfit!" This is usually because people didn't ask questions, used bad form and didn't ask for help, or scaled. The coaches will push you when they think you need it; if something seems to hard for you, don't be afraid to scale.
I went in having done a lot of primal blueprint fitness stuff. I was walking A LOT and pretty consistent with lifting heavy things, at body weight. Still, I never pushed myself the way you will be pushed with the intervals during a wod. It's easier on your own to take your time through a wod, but the atmosphere in the box will drive you to work harder. The other thing is there probably WILL be a lot of yelling and encouragement. I'm in the military and it can at times be close to a bootcamp atmosphere.
I saw this in a couple other places, but the best things you can do are mobility and flexibility work. When I first started PBF I could not do an air squat and keep my heels on the ground. By the time I got to crossfit, I was starting to get better but hadn't gotten good. Now, almost a year later, I have slowly developed the flexibility to do a proper squat. It's been a long process.
Most of all, don't get discouraged! People train for years at Crossfit to get to the level where they are doing prescribed and killing the workouts. Hopefully you find the means to stick with it past four months, because personally I have a hard time maintaining intensity on my own, but that may just be a personal thing. Good luck and let us know how it goes!
~All luck is earned in the end.~