One thing I have learned about my eBuggy as compared to my Nitro Truggy is it seems to react a LOT to brake input while in the air, so one suggestion for you would be to practice your takeoffs and try to NOT correct mid air. It will just mess you up at first. The best way to jump is to concentrate on your takeoff anyway. If you have the right approach, the right speed, and you hit it square (or angled if need be) then you will almost always downside it perfectly. If you give it too much and launch nose high....you can save it, once you get used to it, but you will probably crash quite a bit at first.
Ideally you want to be on power when the car leaves the ground. Now this might be wide open for huge jumps...or maybe you are only at 5-10% throttle, but either way...you want to be ON power otherwise you will find your nose will be too low. You also want to get off the throttle as soon as you are in the air, or you will find your nose up high. Just hop back on the power slightly before you hit the ground and it should smooth things out pretty well if you hit the downside...or close to it.
So applying the brakes on the jump approach is fine, just do it enough before the car leaves the ground that you can be back on power just before it takes off. Now for some jumps...you might want to be off power and a lot of the jumping techniques are of course situational and driver preference, but general rule of thumb is to be on power ;-) Start there and see what works for YOU.
We can give you all the tips in the world on how WE do things, but if your not comfortable doing them or can't master them or whatever....they are just useless tips to you.
I learned a lot of thing racing motocross for many years, and believe it or not it transitions REALLY well to RC Cars. All the same physics, WAAAY different perception. One tip from the pros I got while racing motocross was to drag my front brake ever so slightly when in a rut and it will prevent the front wheel from jumping out of the rut.....no matter what I did I never could master that tip. I'd always grab too much and crash, or not enough and still jump the rut....or I'd forget to do it and make it through the rut just fine. So to me it was a useless tip to improve MY riding.
Just drive and you will learn VERY quickly what works and what does not... I started racing last season, went from a mid to back of the pack driver to TQing the last club race Sportsman class. All I did was drive more....