-Arms and hands are the safest places to shoot.
-If you can't find a vein, warm up the area or do some push-ups to make the vein more prominent.
-Use a fresh needle, and alcohol wipe the spot down first.
-Always shoot toward the heart.
-If you're tying off, release tourniquet before/as you're shooting.
-Draw the plunger back first to make sure blood flows in, so you know you hit a vein.
-Don't share equipment.
Ice dissolves in water, so you can back-load it quite easily. (Take out plunger, put ice in back of needle, put in plunger, draw up water, gently shake.)