firstly before you inject you must clean the site with a alcohol swab. before loading the barrel maksure the liquid is body tempreture as oil generally thikens when cold causing pain lumps bumps etc..then by using a clen 'new' needle inject but before loading the juice in your muscle asperate to see ther is no blood in the vial, then you may inject the juice.once done you must gently massage the area for a few mins and keep clean to avoid any infection. use a plaster!