If you have a few words with the nurse or the doctors before the injection, you'll definitely be more relaxed and you'll already feel a bit less scared of needles. The doctor will talk to you about your options for having the injection and will take all the necessary precautions to ensure that the process is less painful and to reduce your fear of needles.
If you're scared of needles, raise your legs just before the injection; it's a move that can help to distract you and relieve some of the symptoms of your needle phobia, because above all it sends blood to the brain. Having your legs raised and your head lower will help you to avoid the "risk of fainting" at the sight of the needle.
To overcome the fear of needles, you can ask a friend or two to come along with you to the injection appointment, and they'll help to reassure you. If instead you're on your own, count sheep backwards or listen to music with your headphones to distract yourself from the injection. In that way your brain will certainly be kept busy!
If you choose to have the injection in the buttocks, you won't see the needle when it goes in. In some cases this is a trick that can help reduce your fear.
Before having an injection, and to overcome your fear of needles, remember that you have to have complete confidence in the doctors and nurses: they've been chosen to do the job based also on their ability to give injections as painlessly as possible.
If you're determined to overcome your fear of needles, no matter what, here's a quick route: look right at the needle during the injection and you'll feel less pain. According to recent scientific research, you can only get over a fear of needles by direct face-to-face contact with the "executioner".