I'm just going to go over the entire proceedure.
You start out with a bottle of spring water, a clean needle (preferably a 1/2-1 CC BD 29 gauge insulin syringe), a sterile q-tip right from the box, a clean spoon and an alcohol wipe or two.
First, clean your hands with the alcohol wipe.
Wipe the spoon with an alcohol wipe. Put your heroin in the spoon. Draw up how ever much water you want to use and put that in the spoon. Use the end cap from the syringe (the one on the back with the large flat end). Stir.
You do not need to heat the solution. If you do, you should NOT boil the water, just heat it up. But since you keep missing the veins you could end up damaging nerves and tissue if you're using really hot water. So I would definantly suggest you not heat the solution until you learn how to do this right.
Take a piece of the q-tip cotton and roll it into a TIGHT ball, the smaller the better but you want to make sure it's big enough that you're sucking up water from inside the cotton and the needle isn't simply going through. You do this to avoid shooting particles.
Clean the injection spot with the alcohol wipe.
Stick the needle in the cotton (being careful not to poke the needle through hitting the spoon). Draw up the water.
Hold the needle facing your body and inject at an angle. Somewhere between 20-35 degrees is good. You want it to be fairly parallel to your vein.
Stick it in deep then pull it back just slightly. Then pull the plunger back. If you're in the vein you will see a burst of blood rush into the syringe like a mushroom cloud. If you pull back and only get air or the blood doesn't rush in, you're not in the vein and you need to adjust a little bit.
Once you're in, push the plunger and inject the heroin at a medium speed. Not too slow, but not too fast.
One question I have is are you using extra long needles or short needles? You want to use the long needles.
My guess is either you're using short needles and not getting in the vein, or you're using long needles and poking all the way through on the other side.
Another thing is that if you don't have someone with you that knows how to inject, you shouldn't be injecting heroin at all. Your lack of experience could cause you to get an infection, collapse a vein, damage nerves or you may just end up overdosing.
One last thing, if you're satisfied with the highs you're getting now, USE LESS. Because the rush and highs will be far more intense if you actually manage to inject into the vein.