For me the HP .45 was about the most accurate thing I've shot. With that long 4.5 in barrell, it is highly accurate. Now, the gun is heavy. You have to hold onto it, tho. Initially my grip was a little loose. Not limpwristing per se, but I have small hands, so I had to hold it a little more firmly than I would have had to a lighter gun. Also, the way you pull the trigger does make a difference. Keep reading.
Squeeze slowly but consistently. Use followthrough with the trigger and with the shot. Think of it like swinging a baseball bat. The bat doesn't stop once the ball is hit. The bat is expecting to come on around, and if you try to check your swing once the bat is contacted by the ball, you'll not be hitting well. Same is true of golf, tennis, billiards, etc. This also applies to shooting on two levels. When you squeeze the trigger, allow your finger to follow-through the trigger pull. Doing so will prevent you making "triggering" errors.
Also remember that although the bullet is traveling very fast, it still has to travel down the barrell and exit the muzzle, so you have to consciously hold the gun in good aim until the bullet leaves the muzzle. You might not think so, but relaxing the grip for even a fraction of a second after the trigger is pulled can and does affect bullet trajectory.
Also, you might think about shooting stance. The standard stance, gun held in both hands centered in front of the body, works for most shooters, but I noticed that the way I look down the sights, the modified weaver stance works better for me. You can find lots of info here about shotting stance and find one that works best for you.
MOST IMPORTANTLY! Don't get frustrated frustrated and give up. Every person here has had troubles shooting at tone time or another, and every gun is different. Sometimes its about getting used to you gun. Much the same as driving a motocyle is different from driving a bicycle and you just have to get used to it, and practice, and determine that you can do it!