How to inject heroin #4?

[TSLexi]

This is just for reference, as I don't plan to inject (at least right now) heroin, I much prefer smoking it, how do you go about it?

I know to sterilize the injection site, make sure there's no air bubbles, and confirm that you're in the vein by drawing back to fill the syringe with blood, but how do you prepare the heroin #4 (I refuse to inject black tar heroin,that's just nasty) for injection, and give the injection?

I have 10x 31g 5/16" single-use insulin syringes. How sharp are these needles?

Thanks!