Some things to keep in mind going to 3s
1 - The Dp shortcut is still there, but you have to start from DOWN, so if you input d, df, d, df + P then you get a dragon punch.
2 - The super shortcut in 3s is NOT the same as the super shortcut in sf4. In sf4 you can get super by doing d, df, d, df, f + button, in 3s it's qcf, d, df + P. You HAVE to complete the first qcf, but on the 2nd half all you need to do is d, df, if you have a square gate this is really easy to get a hang of as you just think of it as doing a circle then mashing the stick into the corner.
3 - If you want to carry your sf4 reversals to 3s..........anytime you want to reversal, parry first and THEN do your move, it's theoretically almost the same thing except you lose to throws, unless you OS it of course.. The reversal window in 4 is 5 frames, the parry window in 3s is 7 frames, so any time you want to throw out a risky reversal, just remember to parry first.
Couple of things that might help you out while playing the game.....
Footsy Parries - Off the top of my head, urien is the only exception I can think to this, but almost no characters can get big damage off a mid poke at whiff punish or max poke range in this game, so rule of thumb is if you want to try to parry a limb, risk/reward is always stacked towards a LOW parry at footsies, because cr. mk's lead to supers, then setup, then mixup, etc. etc.
TL;DR at footsies range parry low!
Throw techs - There's two ways most players tech in this game :
1 - Down Back + short + Jab, which gets you a tech if they throw, or a short if they don't. Keep in mind though that this will get you blown up by a low parry, but depending on your character and your crouch short's recovery, the other player might not necessarily get a big punish off it.
2 - Tap forward, slight wait + short + Jab - This gets you a throw animation (and thus a tech) if they throw or don't press a button, or a parry if they did a meaty mid. This will beat people doing nothing on your wake up trying to bait a button(they'll get thrown), a throw, and mids. Just be ready to either punish the mid if you parry, or if you get a read then continue the parry if they're chaining off the mid. This WILL get blown up by command grabs and back dashes, as the grab just straight beats it, and the back dash leaves you in throw whiff animation.
Parries!!
Beginner advice...don't parry too much! Just block and whiff punish! It's good! More often than not if you go up against an intermediate or advance player, they WILL option select a parry every chance they get, so just sitting back and punishing the whiff (as the OS dictates, if they don't get a parry, they get something else.) Backdashing on someone's wakeup is also good as lots of characters like to do (sf4 lingo here reversal ultra) attacks that lead to big damage off a parry. Ex - you have Oro knocked down, he's KILLING to land a close st. mp, so chances are on his wakeup he's going to lead off with a mid parry, hoping to catch something then cancel to his cl. st. mp. Backdashing and punishing here will beat him clean.
Well hopefully that helps peeps out a bit, anything else just ask yo! I may not agree with 3s mechanics and overall design in the context of it being a street fighter/fighting game, but in and of itself i think the game is fun, and it's not as hard to get over the learning barrier in this game as people make it out to be, it's pretty simple actually!