For most people, just reaching the state of "mind awake - body asleep" (some prefer to say "soul awake - body asleep") is perfectly sufficient for moving out of the body. There are techniques also which while not necessary. They could be of interest:

In Robert Monroes book titled 'Journeys Out of the Body' he describes his own technique for inducing OOBEs. It starts with what he calls the "vibrational state". Often an OOBE start with a vibrating or shaking feeling in the body.
He suggests the following: Lie down with your head pointing to magnetic north. Personally I don't know how important that is. The out of body experiences I've had, my head was not facing north, but then I never tried facing north, so I can't really comment on that. Make sure you are comfortable, so remove glasses, watch, wear comfortable clothes etc and stay warm. Make sure you wont be disturbed and that you have lots of time. Robert then starts with relaxing and then repeating to himself five times: "I will consciously perceive and remember all that I encounter during this relaxation procedure. I will recall in detail when I am completely awake only those matters which will be beneficial to my physical and mental being." Then begin breathing through your half-open mouth.
While entering the hypnagogic state (as described on this page above), Monroe recommends to deepen it by clearing your mind and observe your field of vision through your closed eyes. Do nothing more for a while. Just look through your closed eyelids at the blackness in front of you. After a while, you may see swirling colors, light patterns, hear sounds etc. Robert says these are neural discharges and have no real value in themselves. When they decline and stop, that is what Robert Monroe calls Condition B. Then one needs to relax even deeper while remaining awake (mind awake - body asleep) and reach what Robert calls Condition C - a state where you are not aware of the body and sensory stimulation (might feel like it isn't there, or you are simply unaware of it completely). As you get even deeper and all that is left is your own thoughts, this is what Robert Monroe calls Condition D and is the ultimate state to leave the body. Being rested and reaching this state voluntarily is the most important part according to Robert and recommends doing it in the morning or after a nap.
Then comes the actual technique: look into the blackness about one foot (30 cm) from your forehead and concentrate on that point. Then move focus gradually to three feet away (about 90 cm), then six feet (180cm) and then turn focus 90 degrees upward from that point, above your head. Monroe says you can then feel vibrations at that spot which you should mentally "pull into your head". He describes the vibration as a surging, hissing, rhythmically pulsating. Then these vibrations go throughout the body, making the body immobile. It is said that this is not as complicated as it sounds. If you have heard a clear buzzing or hissing while falling asleep, you may understand why it isn't as hard as it seems, since you've already been there.
Monroe says once you reach this state it is not possible to turn back. You can then try lifting an arm or trying to grab something out of reach and putting the arm back where it was.
To then leave the body fully, Robert uses what he calls the "lift-out" technique by simply imagining getting lighter and lighter, until lifting out of the body. Other techniques are:
Float out - visualize your viewpoint has risen a few feet into the air
Swing out - visualize a swing forming long arcs as you gain momentum
Sink out - imagine your dream body slowly dropping through the bed
Roll out - visualize yourself turning on your side and rolling over
Teleport out - imagine another location and engage your senses
What it comes down to is simply being awake while the body is asleep and I look at Roberts method as a good guideline in which you can experiment. The out of body experiences I have had myself have not involved this method at all. They have all been after laying down after third eye mediation, falling asleep and then waking up deciding to get up from bed and the body then remaining in bed, so it doesn't have to be complex at all.