Standing is all about fundamentals, patience, and discipline. I'm a smallbore shooter at heart who is venturing into high power and completely agree that high power shooters make average SB shooters. HP shooter arrive at a SB match and we say this should be interesting. SB shooter go to a HP match and the HP folks say "uh oh".
You should use smallbore to train for HP since you have to have better fundamentals to find success. Air rifle would be even better since you can do it at home, and air stresses fundamentals even more then SB.
First, as has been said, a relaxed position is required. As for putting your elbow on your hip, that will depend on your build. If you can do it and still aim in the right direction, then go for it. If you have to push your hip out to do it, don't. I'm 6-2 and can't do it, so I'm very upright with my elbow on my rib cage. Experiment with elbow placement (try to avoid moving it towards your chest). You'll know you have a good position when you can stay in position for a minute or so with no discomfort.
Next is Natural Point of Aim (NPA). I didn't see anyone mention this. Start training without a target. Learn to get in position the exact same way before you dry fire a single shot. To give you an idea on how accurate you can be with this, I can, with my SB rifle, get in position with the sights blocked out and put a shot in the black. That took a ton of practice, but there's a goal for you. I'm still working to be that accurate in HP.
After that is shot selection. Learn to reject shots. I don't seem HP shooters doing this too often. Picking the rifle up and then seeing the shot is not there is NOT A BAD THING. Learn to reject a lot of shots now. The minute you hear he thought in your head "I can still get a 10 out of this", stop and put it down. This will get you to recognize the good shots and learn how to repeat them.
Lastly is training. Not practice, training. Training has goals and structure. a few drills you can use:
Groups - your best friend. Could be anywhere between 3 and 10 shots. Don't look at the target for the whole group. If you need to move the sights, do it between groups. I suggest starting with 5 shot groups.
NPA Training - two ways to do this. First is on a single bull. Shoot a shot, get out of position, get back in position, try to double the shot. Second way, on a multi-bull target, choose a bull at random and fire a 3 shot group at it (remember no looking). Then choose another random bull, another 3 shot group. If the second group is off to a certain direction, say the bull you just came from, you know you need to be more disciplined in your NPA.
Strings of 10s - You can also do this with 9s, 8s, etc based on your skill level. Simply put a target up and see how many you can get in a row. Challenge yourself to up your record. Once you master the 8s, go to the 9s.
Number of 10s - Choose a number of 10s you have to shoot (10 is a good number), and record the number of shots it takes you to get there. Try to beat your record.
Endurance Training - learn to shoot longer than you need to. I've trained to shooting 60 straight shots offhand in an air rifle match, so the 10 I've had to do in HP don't even phase me. A well built standing position should actually shoot BETTER as you tire out since you lose the energy to muscle the gun around.
If you would like a simple phrase, here's mine: "Shoot 10s". When you realize the greater meaning in that, you'll have arrived.