Alright, we know the basic principles of riding are: heels down, eyes up (looking where you want to go), shoulders back, and sit tall, right? Now, here are step by step details:
1) Approaching the fence
Don't forget that the approach is a very important part to the jumping process! As you begin to ride up to the fence, you mustn't move your eyes from the straight line you see to, and from it. If you are coming around a turn, try not to lean, but to sit up, and execute a nice, wide turn (except in jumpers), giving your horse plenty of time to see the fence and prepare for it. During this time, you should continue to look at the line (but NEVER down at the fence), while sitting tall, and keeping those basics we discussed in mind. Often (depends on what your trainer wants), you should half-seat the canter(hover over the saddle) or sit the trot the last few strides, while STILL keeping your basics.
2. Take-Off
Keep in mind that your horse, while looking to you for guidance, is trying to find a distance that will be most comfortable to take off. It's usually the job of the rider to determine the pace you need in order to meet your ideal take-off point. However, if you are not yet used to this, then avoid interfering with your horse. Some horses are very scopey, and can find the pace themselves, but don't worry about that for now. We know that the horse will take off a few feet from the fence, but NEVER anticipate the jump. Doing so will cause your body to naturally get ahead of the horse's motion, unbalancing the horse, and increasing the chances of either a chip (quick, short step horse makes...like, instead of getting four strides, it feels like the horse got four and a half) or a refusal. So, sit up tall, and look straight past the fence...only begin to two point when you actually feel the horse's body begin to lift itself over the fence. This allows you to use the natural thrust of the horse to help push you up out of the saddle into the two-point. So, as you begin to two point, the following should happen:
--You FLEX those heels down, turning your toes JUST a bit out, just enough to press your calf against the horse.
--Distribute contact/pressure evenly throughout your leg...don't grip too much with the knee! This is very common and causes the lower leg to slip back and the upper body to dip forward, as the knee acts like a pivot. So, wrap that entire leg around the horse!
--Begin to bring your upper body closer to your horse's neck. The degree of your two-point should about match the degree of your horse's motion (smaller fences, don't need as exaggerated of a two point as larger fences obviously). Let your upper body follow the flow of your horse's neck.
--Don't use your irons/leg so much to bring that butt out of the saddle. As I said, the horse's thrust will help you out there. You DO want to be off the horse's back, but you also don't want your butt too high out of the saddle.
--One of the most important parts--the crest release. Let your hands come forward, up the horse's neck. About half-way up the neck, your hands should press into your horse's crest, giving you stability, while providing your horse with plenty of room to freely move it's head (you should never hit the horse in the mouth...most likely, it will happen someday, but avoid this as much as possible!).
--Keep those eye's up and looking ahead!! This will help you keep your back straight.
--shoulders back
3. Midair
Alright, in midair is where we see the two-point in full action! You should do/have the following:
--KEEP LOOKING AHEAD TO WHERE YOU WANT TO GO! Moving your head, without you even knowing it, completely shifts your weight, and throws you, and your horse, off balance. Plus, by not looking down, your back will more easily stay straight and flat.
--As for the legs, you still want your heels down, toes turned out slightly, calf against the horse, contact/grip distributed throughout thigh, knee, and calf. And, very important, your leg must be BENEATH you. Don't let it slide back--or forward for that matter.
--Your butt should be hovering over the center of the saddle right now, just a few inches above the seat. It should be neither above the pommel or the cantle, but hovering over the middle.
--Your back should be flat, preferable with a slightly concave-appearance...that slight arch will allow you to stay secure over the fence.
--Your shoulders should still be nice and square, not rolled forward.
--Your crest release, as I said, should be half-way up the horse's neck, with your hands pressing into the horse's crest. Also, DON'T kink your wrist. There should be a straight line from the elbow through the hand.
--Get ready for landing! If you are cantering, and need a specific lead, lean into the iron that is opposite of whatever lead you need. This causes the horse to land on that lead as it canters from the fence. However, don't worry about this until you have good form, or else you may accidentally interfere with the horse.
4)Landing
Landing is also a very important aspect. As you land, the following should take place:
--As always, LOOK WHERE YOU WANT TO GO! This will cause slight reactions in your body that will (usually) help the horse understand where you plan to go.
--Now, here's a tricky part. DON'T CHANGE A THING! You should land in your two-point, and stay in a two pointish position for about one stride afterward. Let your horse finish the jump before sitting up and moving on. Some slight changes will happen, but what I mean is that you want to continue to stay off the horse's back...so you still want:
--heels down!
--Your leg should remain directly beneath you...if anything, a little forward, but preferably not (unless you're jumping a bank!).
--Still let your hands follow your horse's neck and mouth.
--still keep your butt off your horse's back.
--Sit up just a bit taller. You shouldn't be bolt upright, but don't be crouched over the neck...find a mid point...kinda like the half-seat.
And continue on nice and smoothly!!
I hope this helps ^_^
Tips for keeping balance:
--ALWAYS LOOK WHERE YOU WANT TO GO!!
--Shoulders WAY WAY WAY back...exaggerate it until it becomes natural, so that you never have to worry about hunching. I used to get ahead of the horse, but by doing this, I was forced to not hunch, and was able to wait for my horse before two-pointing.
--Always push those heels down
--For me, I have to remind myself to keep my hands up...I have a habit of riding with low hands, and so when I would jump, I'd have my hands below the mane, so I would fall forward because I didn't have anything for support. So, a couple strides out, I remind myself "hands up!" and my hands just naturally go into a crest release. It made an amazing and fast change to my equitation.
PS--When in doubt, GRAB MANE!!! It's helped me many times. Especially if I am approaching a fence that the horse I'm riding is unfamiliar with. You can sorta feel the horse hesitate, and also look at their body language. If you think they're going to take a long spot or possibly refuse, grab mane so that you stay with them.