well, take anyones advice with a grain of salt. not that im attacking stickys advice as it is very sound. im basically attacking the advice i give as this game isnt figured out yet so, any advice is suspect:
NEUTRAL GAME:
this is the biggest problem and that thing that anyone has to learn in order to be good at any “good” fighting game.
neutral game i basically define as that part of the game where neither character has any kind of positional advantage such as knockdown, being at plus or minus frames etc. the round starts at neutral.
anywho, learning neutral is key. learning that there are mixups in neutral, how to apply them, what they are, how to defend against them, how to read them, how to keep yourself out of easy to beat patterns etc etc.
for instance im a painwheel player. painwheels neutral is both ridiculously good and not so great at the same time. its ridiculously good because painwheel has access to fly for harrassing other characters from high in the air and using that as a way in. its not so great because painwheels ground options are somewhat lackluster compared to your typical rushdown character… this basically means that painwheel NEEDS to fly in order to maximize her strengths. this makes her an obvious character. however to keep this on topic the reason why i mention tis is so that you can understand that there is something that painwheel is going to be generally always looking for and that is… to take to the skies.
this is why gtfo assists AT THIS POINT seem to be mandatory for her… they clear space for her to get into the air. even if the assist wiffs she still gets into the air… and once there shes REALLY good. Without having that it can be very hard for her to get to that position since she doesnt really have any gtfo moves and flights startup is slow.
now, once in the air she has amazing tools and this is where the neutral game mixups really start to come in:
if im above my opponent i can choose to come down with j.mk for a direct, high priority attack that puts me in the opponents face with frame advantage, that attack also doubles as a hitconfirm. now im not going to go into all the theoretical mixups i could do here… they are vast. ill simply talk about the j.mk itself, if i do it right when i get into range, im being predictable, my opponent can anticipate this and try and air to air me. they can also call out an AA assist to hit me, or try and airthrow me… etc etc… basically they have counters. so instead of just doing j.mk as soon as i can i may want to jiggle back in forth in the air while im flying, so that i can try and bait there AA assist or jump attack after all if they wiff a jump attack on me then i can come in easily as they are landing.
bla bla. the point is that your opponent will probably have neutral game mixups such as this that have to do with air dashing/not air dashing… using rushdown moves that have armor, baiting by double jumping backwards etc that you will have to see and know how to exploit if you can read patterns well and punish them for. its really hard in a game like this cause of the myriad of options that an opponent has at there disposal… but there is one caveat to that:
SINCE THERE ARE SO MANY OPTIONS AND SO VARIED, THE OPPONENT WILL LIKELY DISTILL THOSE OPTIONS INTO A SELECT FEW SO THAT THEY CAN MORE EASILY CONTROL EXACTLY WHAT THEY ARE DOING.
theres probably a better way to say what i just said… i hope you get what im saying, which is basically that even though your opponent has perhaps hundreds of ways to mix you up in neutral and probably just as more to mix you up on the ground/during resets… they will probably stick to a few tried and true patterns… learn them and you will have a MUCH easier time defending against them and knowing how to attack them.
the better the player usually means that they have more practiced patters to go to, or they knwo a shitload of defensive patterns upon which to rely or a combination of the two.
anywho, ive written way to much… probably to no avail. so ill just leave you with the most obvious ways to react to rushdown:
chicken block (jump backwards) this gets you away from high/throw mixups almost completely and it avoids slower low mixups… its the best “overall” defense in the game.
call invincible AA assist (primarily use this as a way of dealing with very obviously TIMED jumpins) unfortunately these all come 2 frames of hittability on the startup of them so they arent exactly braindead gtfo maoves and have can definitely be stuffed in startup by meaty jumps and if your assist decides to come out in the middle of an opponents ground chain (which means that you guessed wrong/didnt know how to properly use your assist/timed your assist wrong) < when this happens you need to KNOW which of those 3 it was so that you make the mistake less or you will be doomed to repeat it (this is once again, just pattern recognition)
how to deal with someone that dashed in against you and put you into grounded string that would have hit your assist if you had called it? call the assist then PUSHBLOCK YOUR OPPONENT. this kind of requires decent anticipation though. note that this can also apply to using your assist as an AA… its what mike z does when he calls out cerebellas command grab assist then pushblocks his jumping opponent…they get push blocked INTO cerebellas grab… smart stuff but you dont need a grab assist to make use of the pattern.
anywho… thats ALOT to take in, and chances are that you already know most of that, but its always good for someone to say obvious things just to bring them more to light. also, just knowing any of this wont make you any better, its actually going out and using these things in your game at the right time that will make you better, and that only comes with practice against people.
and as i said at the beginning of this wall of text… take anything i say with a grain of salt. use only what you find useable or understand, trash everything else.
good luck 
-dime
