1. Preparation:
• Gather your supplies. This will typically include your Semaglutide vial, a new syringe and needle, and alcohol pads.
• Clean your hands thoroughly with soap and warm water.
• Choose your injection site. For subcutaneous injections, this is often the abdomen, thigh, or the upper arm.
• Clean the injection site with an alcohol wipe and let it air dry.
2. Prepare the Syringe:
• Remove the cap from the Semaglutide vial.
• Clean the rubber stopper on the vial with a new alcohol pad.
• Draw air into the syringe equivalent to the amount of Semaglutide you are going to inject. This is done to equalize the pressure in the vial when you extract the medication.
• Insert the needle into the vial and push the plunger to inject the air into the vial.
• Without removing the needle, turn the vial upside down, make sure the needle is beneath the fluid level, and draw the desired amount of Semaglutide into the syringe.
• Remove any air bubbles in the syringe by gently tapping the syringe with your fingers until the bubbles rise to the top. You can then press the plunger slightly until the bubbles are gone. 
3. Administer the Injection:
• Pinch the skin at the injection site.
• Hold the syringe like a dart, and insert the needle into the skin at a 45-90 degree angle.
• Once the needle is in, release the pinched skin, and slowly depress the plunger to inject the Semaglutide.
• Once the medication is fully injected, quickly pull out the needle.
• Discard the used syringe and needle in a sharps container for proper disposal. 
4. Aftercare:
• Apply a band-aid to the injection site if necessary.
• If you experience any adverse reactions, such as nausea, vomiting, rapid heartbeat, or difficulty breathing, seek medical attention immediately.

Safety is crucial when administering injections at home. A healthcare professional should be the one to administer the injection. Self-administration should only be done under the guidance and approval of a healthcare provider.