Tim, such guns are made for close shooting. Not to say you can't hit further out, but figure if you're a greenhorn like you say, set up a target no further out than five yards. Get your gun hand as high up on the handle as it will go, hold the gun GENTLY in the center of your hand so that the barrel lines up with your forearm bones, and wrap your support hand over the gun hand with the support wrist cranked downwards sharply so your support hand thumb is lined parallel to the barrel. Grip hard with the support hand, weak with the gun hand. Concentrate on getting perfect sight alignment, focus on the top surface of the front sight, and get a gentle slow trigger press straight rearwards (don't be pushing or pulling the gun sideways with your trigger pull) that does not disturb your aim. Try to have the shot come as a surprise every time. When you are putting them all in a big ragged hole, move the target back a few yards and repeat...and repeat...etc. Good sight aligment, focusing on the sights, and a surprise-break trigger press that does not disturb the gun will get you a hit every time.
After a while you'll note your eye automatically goes to the sight as soon as the gun is raised, your press will speed up while still being a surprise, and you'll be able to both shoot quickly and accurately at close range, as well as being able to hit a smaller target further away. Keep your focus on the sights during and after the shot so as to see the gun come down from recoil to its original position which will present you with a sight picture again. This allows fast accurate follow-up shots. Lean your upper body weight slightly forwards into the gun, this helps absorb recoil and helps bring the gun back into alignment more quickly.
Remember, focus on the sights, get perfect sight alignment, don't fire if the alignment is bad, and get that gentle surprise trigger break. No one can hold a gun perfectly steady, so don't let a little gun wobble bother you. However, make sure that the sights are always in as perfect alignment as you can get within the wobble. This way you'll always hit within your wobble pattern. But, if the sights are out of alignment, this means the gun is aiming at a different angle than your eye is looking, which means your hit will be way way off where the gun 'appears' to be aiming.
If you get to the point of shooting a quick double at say 5 yards less than half a second apart, seeing your sights both shots, and hitting more or less center but three or four inches apart, you're doing well enough for defensive purposes. If you can hit a coffee can every shot at 25 yards in slow fire, that's very good too. Of course there is no end to how far you can take your skill beyond that.
You probably want the 4" barrel to start, the longer ones are a little easier to shoot well with a longer sight radius.
You can practice most of this in dry fire, just don't accidentally blow up your TV. ;-) Hope this helps, let us know how it goes.
