Injection Tips for Needle Nervous
From someone who had to deal with a fear of needles while learning how to do testosterone shots. To be clear, I'm 28 years old and have been doing weekly IM injections in my thighs for 18 months.
PREP -Listen to the information given for the possible injection sites; you may prefer or find it easier to deal with IM vs SubQ based on the options your doctor gives you. If you're able, schedule at least 6-8 injection days of clinic visits so a nurse can teach you how to inject properly, and you can take your time absorbing. If you're still nervous, try purchasing a 'shot blocker' since they can help with not feeling the needle. If it's the possible pain that bothers you, I used to pinch hard at the area with my nails to sort of say 'that's what you're expecting, see, it's not that bad!' This technique has also helped me with getting my blood drawn, which to go on T you'll have to deal with as well.
ROUTINE -Once I left the supervision of the clinic nurses and started injecting at home, I made sure to establish a routine. You'll need to find your own, and here's mine for reference; with a little wiggle room (like doing it in the morning if I know I'll be busy in the evening) I stick to the same rhythm every week. Set up my station, use the toilet (you don't want to be antsy handling a needle), press play on a song and wash hands, then my draw system [sanitize stopper, draw, switch needle size, get rid of air bubbles, adjust to relax, sanitize thigh, breathe, inject, pressure with a tissue until the song ends], then I clean up and put the needles immediately in my sharps box. It really helps to know exactly what you're getting into so unexpected changes (like injecting while a little drunk, I don't recommend this but it might happen) are easier to handle.
DISCIPLINE -I put on a 5 minute song and do my whole routine in that time, it works for me. Too short and you'll feel rushed, too long and you might procrastinate, so get into the habit. I give myself a four hour window and as soon as I feel like I could do it, I go for it.
CHILL -As mentioned, I put on a song, for me stoner metal or blues works the best since it soothes and zones me in. I do my shot in the evening so if I freak out a bit I can just go to bed. I put on my comfiest layers and have a treat after, too.
EXPERIMENT -While there are aspects of it all you must do a certain way, you won't always know the best way to do things for yourself of available options even once you've been taught, so let yourself feel it out. I was shown the quick jab method at first to get over my hesitation, but now I find I feel it less if I insert the needle slowly. I switched from 25G to 22G needles when the smaller size proved more difficult to inject due to the consistency of testosterone, and I also found a shorter needle length got rid of some residual anxiety over the actual insertion part. I used to do everything in the morning and now I solely do it in the evening. You can change some parts of the process to make yourself feel better! 
FRIEND -I've got an assistant who sits on my other leg while I go through my routine, his name is Snippers;
And I've found I'm less jittery with him there and my heart races less in the preamble to actually piercing skin. I keep him with me afterwards especially if I had a harder time than usual, which can happen even after doing this a long time.
And lastly;
BELAY THAT -Give yourself an out. Besides a situation like if I run out before my prescription can get refilled, I told myself I could skip one (1) injection per year, if I was having a super bad time and just couldn't. So far I haven't had to use it -at the most I've just waited until the next evening. My doctor has said that's fine and I don't have to inform her if I skip once, but that might not be the same for everyone. Either way I think giving yourself breathing room is essential to take the pressure off -self-injecting might be affirming, but it isn't always fun or easy!
I also think it should go without saying that these tips are things that have helped based on my own personal experience from the past year and a half. It's fine if they don't work for you or you don't think they're helpful at all -the trans* experience is wide and varied. I'm also not giving anyone medical advice -always learn how to properly administer your medication from a professional. Here is an article about general HRT self injection that may be some help.
But, if you do have difficulty with needles, hopefully this gave you some tips and tricks that could make the process feel more manageable.
