Some testosterone medications such as Sustanon are supplied in glass ampules and there is a simple technique to opening them easily and safely:
Gently tap or flick the top so any medication in the neck flows into the bottom.
Clean the neck with an alcohol swab.
Notice that there is a dot above the neck. Hold the ampule upright, below the neck in your non-dominant hand, with the dot facing towards you.
Place the thumb of your dominant hand on the dot.
Snap the top away from your body in one quick, firm motion at the neck.
Discard the top immediately into a sharps container.
Use a filter needle to draw up the medication.