Kay.
Race It - Don't jump on ramps, the goal is get enough juice so you can get a full Tricky bar, that way you can glide across the stage with boost, enabling you to win. That's actually not accurate, it's not so much that you shouldn't jump on ramps, but know when to jump on ramps. You want to jump, but you want to avoid big air jumps. Use tricks without using big air, you want to get as much Tricky bar and boost as possible while avoiding big air. If your ramp is going uphill jump. If you're going downhill try to hit the shallow end of ramp so you can glide across the plain without gaining air. You will fall faster and gain more speed on your downward descent at the same time. Also, a big tip when you do jump uphill is to wind up a move.
Winding up allows you to do tricks faster while in the air. So let's say, the first ramp on Race It track in the demo, hit the flare for a speed boost (these are great for gaining speed boosts when you've got little boost, hit as many flares as you can) then hit the boost button, hold A to crouch and prepare your jump, hold left, down, or right - you will see your rider wrap their body in the direction you're holding the button, once you hit the ramp release jump, keep holding the wind up while tricking in mid-air. You will notice that the wind up allows your trick to go faster, this is key to gaining speed, boost, and tricky meter in a fast time.
I'm not sure what the controls are for the 360 version yet but use LT to maneuver around sharp turns.
Know your route. Watch the video I posted for Race It. Each route has its advantages and disadvantages.
Basically, in Race It, your goal is to gain boost as fast as possible and keep a consistent chain without losing speed or boost, that way you can gain more speed than your opponent. Very cerebral racing.
Watch EA's very own Race It demo tips and tricks vid.
Trick It - Like I said above, the key to gaining points in this version of SSX is combo. This was true for SSX3, and since you haven't played that game, it'll be hard to explain, but the general idea is to have the biggest combo you possibly can. A combo basically means, you're doing tricks and each trick adds to your combo. If you delay tricking for a few seconds you lose your combo. It's about 1 second in game time by estimation, I'm not sure; SSX3 had a circle to gauge when you will run out of combo but this game doesn't. This means you need to do anything you can to keep your combo: if you're not near any ramps, do a regular olley jump, or a twist or spin of flip, or better yet do a manual. The thing about manuals is that you have control of them. On the ground, press X or B to do a manual and slowly twirl your analog stick to get a spin. This adds more points and boost.
Anyways, your goal is to get as much Tricky and boost as fast as possible and maintain that. If you use a dupe trick, your combo lowers, and if you keep doing it you lose your combo in general. By keeping a consistent combo and doing more tricks, each new trick adds to a multiplier at the bottom: x1, x2, x3, x4, x5...all the way up to x20. This multplies with your combo, so if you have like 200k combo points, x20, you will bring in millions of points alone so long as you: 1. don't wipe out or 2. lose your combo.
The biggest tip I can give is to change your tricks regular. Go for double grabs more than one button moves. Rotate between X -> Y, Y -> B -> B-> X and throw in a tweak for bonus points. When you regular tricky, start busting out Ubers. Then when you get to Super Tricky, user your unique special Ubers in combination with all the above for a lot of points.
Winning in Trick It takes perseverance, patience, and memorization. Don't button mash. The fact that duping moves takes away points makes this a whole different beast from past SSX games. What's more, when you do trick, use only one move per air. So let's say, you're in the air, and you're preparing a trick. Doing a bunch of tricks in that time span will net you less combo points and points in general compared to say...doing one single X -> Y move, holding it, tweaking it, and adding a x10 flip. You gain more points that way.
Finally, once again, know the track. When you do, you can double the amount of points you gain because especially on the New Zealand stage, there are lots and lots of hills even without indicators. Jump on that shit. There is no time limit. Do whatever you can to do add to your combo with as much variety as possible.
If none of this makes sense, watch EA's own tips and tricks on Trick It.
Since you haven't played SSX3, I should post this as it's hard to understand going from SSX3 to this one, and they're very similar in ideology. Notice how in this vid, the player is doing anything he can to keep that combo, especially spinning manuals. Spinning manual -> trick -> big air -> spinning manual -> uber, it's basically stringing together as much as possible. This version of SSX is similar yet different at the same time.
Ultimately, the gameplay in SSX is fantastic because button mashing is a no no and that was a huge aspect of tricking in past SSX games, and at least from the demo, you have to put more effort into your game.