Place a sterile tube into your tattoo machine with the tube tip pointing towards the front of the machine. Place a disposable rubber grommet on the back of the machine on the armature bar post. When you position the needle into the tube, make sure it is sterile and the end of it flush with the opening of the tube you placed it in. Gently push the needle's eye loop into the grommet. Depress the foot pedal to start the machine. Watch to see the needle move in and out and that it does not go past the end of the tube. Take your foot off the pedal. Make any adjustments before you start your work.
If you are a beginner, it is a good idea to use a 4-inch straight needle for shading and a 3-inch round needle for line work. As you gain more experience, you can experiment and work with needles that suit your personal preference. There are several different sizes and styles to needles to choose from when you get to this point.
Turn the voltage knob to 8.5 or so for shading. This voltage will be higher than the voltage you use for line work. You may have to use a slightly higher voltage if you are working on a fleshy area of the body. The noise from the machine should sound like a steady buzzing or humming when you push on the foot pedal. Unusual or unsteady noises indicate that you need to adjust the voltage. Make this adjustment before you turn the tattoo machine on.
You will want to change the depth of the springs when you are switching between line work and shading. Shading requires less depth and the springs should be loosened for this. The distance between your armature bar and contact screw should be about 2 mm. Twist the contact screw on the top of the device to adjust the spring below it. Make sure to do this adjustment before turning the machine on to work.
Dilute the ink with a little bit of water for a lighter shading effect. Leave it undiluted if you want dark shading. Hold the needle so it is slightly tilted towards the skin. Use the tattoo machine as if you were painting on the skin. Move slowly across the skin if you want darker shading or move faster if you want light shading. Wipe the skin with a clean, damp cloth frequently so you can see what you are doing. Use slightly more pressure for darker shading than you would for lighter shading. Use a little bit of white ink to highlight certain shades. Use the white sparingly though.
For the safety of you and the person being tattooed, always make absolutely sure that you sterilize your equipment before and after you do ink work. Wear rubber gloves during the whole procedure and the cleaning. Safety is very important during tattooing.
Only tattoo other people if you are comfortable with the procedure and have gained knowledge and experience beforehand. If you are a beginner, work with an experienced tattoo artist first. It is a good idea to take some courses and attend some seminars for tattooing to gain more knowledge on the subject.