This post is inspired by a true idiotic friend of mine.
This guy was new to steroids and had come to me for help with setup and so on. He had been training for some years and wanted to take the step into the dark side. The first cycle he had done was test enth at 500mg a week. He went up 10lbs and after pct he had lost 13lbs. I couldn't understand what had gone wrong, as i had explained the PCT programme to him in detail. He then told me, that he had eaten what was close to his maintenance and sometimes a little lower. When he got off the drugs and went into PCT, he had lost his appetite and further decreased his food intake. In the presence of low testosterone, this meant that he had lost more muscle and strength than he had before he started the cycle!!

Some months later he wanted to come back on again, and do everything right. So he contacted me to set up a programme that I myself had had succes with in my beginning. Everything was on point. Until one day in week 3 when he broke an ampoule and spilled 0.3cc on his bathroom table. The IDIOT then thought YOLO and drew it up with the rest as to not miss any gains. Naturally he proceeded to get a lump at the injection site, which got red and swollen. two days later he went to the doctor and got antibiotics to overcome the infection. Luckily he overcame it with no issue, but had to cut the cycle short and go into pct. Once again he lost more than he gained, and now he won't start again (thank god).

Now I hope most of you beginners out there isn't as brainless as my friend here. But I thought no-one was, until I met this guy. Therefore, I want to stress the importance of COMMON SENSE when dealing with stuff you're INJECTING INTO YOUR BODY.

It is common sense, that when take stuff from the outside and put it inside yourself, it NEEDS to be sterile. Sure, your body has an immune system that can fight bacteria and so on. But you really don't need to take chances here. Your needles are packed sterile and your oil should be sterile. Keep it that way. Avoid breathing into or onto your gear or equipment. Avoid exposing the inner parts or connective parts of your needle/syringe more than the time it takes to open and connect.
Always sterilize your ampoules or vial tops with alco-swabs before opening them/stabbing through the membrane. Bacteria CAN get into the oil with broken glass from ampoules or when the needle is stabbed through a dirty membrane. Once it is in, it can easily cultivate and make your gear dirty.
Also, always sterilize your injection site with an alco-swab before injecting. The same way bacteria from a vial can get into the oil, so can bacteria from your skin get into your muscle/blood, which also causes risk of infection.

Another important thing to remember when injecting is to aspirate before. I know this isn't medical practice some places, but the risk of causing an embolism in the lung or heart is very much present IF you happen to inject into the bloodstream. Oil and blood doesn't mix, and this can easily be fatal.