To be truthful, you should eventually reach a point where you can IB attacks on reaction. Just take it to training mode and set Ragna to repeat the pressure you often see. Knowing what your opponent can do is half the battle. Later on you can try practicing with other characters to better understand their options.
When it comes to mixing your opponent up, that's more or less up to you. Your overhead is fast, but it only have a few viable lead-ins, and those happen to be very obvious (IE 2A dash 6A links) and also very poke-able. Not to mention it's very unsafe on block, so make sure you RC that shit if they block it. Also note that the 2A into dashing 6A lead-in looks very similar to one of your tick throw setups (if you're going to go for one, I would recommend 2A 5A whiff on a crouching opponent into throw), and this may prompt the opponent to attempt to tech the throw. Which will beat your overhead. People usually fail to block 6As that come right after an aerial overhead. Most won't think to keep blocking high after that.
Lows often come into play after a feinting j.5B or other aerial overhead that would make your opponent think to block high. There is no set time to overhead or attack low. It's all up to you and how you think your opponent is going to act. Don't be predictable and you'll catch your opponent once in a while. If you are going to low, try to use 2B. Much less reward, but for an equally smaller risk. 3C might net you 3k+, but it's not terribly safe on block. You can cancel into Ice Sword A to make it marginally safer, but it's still -6 or so on block, maybe a little less because of sword travel time, and thus punishable on IB.
Other than that, come up with your own little gimmicks into mixups. Rapid canceling 3C into dash 6A will trip up a lot of opponents. Just don't do it if you actually hit with the 3C.