Deliverance should never be done by new converts, those weak in the faith, or anyone whom Satan can make a legal claim on. Thus a worker who is in deliberate and willful violation of a commandment is opening himself up for trouble. He does not have to be perfect. No one is. But what he does need is (a) complete and utter faith in Christ, and (b) a pure or holy life. He must believe in the promises of the Word of Yahweh utterly because deliverance can never be done in a man's own strength but only in Christ's. There should preferably be at least two workers with one physically present with the victim. Deliverance can be done over the internet or by telephone. If the victim is willing it may be possible to do it alone (as I have often done) using an Internet Chat Room. If the latter, Voice mode is sometimes important in order to audibly rebuke manifesting demons. Voice mode also allows you to respond faster and so not prolong the agony as the victim goes through his last struggle before he is free. If the victim is not willing and Yahweh has given a very clear word to the worker to go ahead anyway, then a couple of very strong men may be needed to physicaly restrain the victim from becoming violent. In their exit-throes, demons can display supernatural strength in their victims. If there is more than one worker, one most always be in overall charge. The other may counsel (especially if he is getting tired and forgetful) making a partnership important. One can hand over charge to the other as necessary.
Make sure that no-one else is around during deliverance. Exiting demons have been known to attack those nearby. Before deliverance is conducted, a special room, with closable door(s) and window(s) must be selected and consecrated with olive oil and prayer in the prescribed way. Keep the room locked. Make sure the victim goes to the toilet before the session begins (I have known victims to be overpowered while in the WC and the session ruined). Make sure there is a plastic jug of water at hand as the victim may use much energy and dehydrate quickly. Remove all objects which might be used for self-mutilation like knives, razor-blades, mirrors, etc.. If the door has a lock, make sure it is locked. If there is a telephone/mobile in the room, take it off the hook or turn it off. Demons have many ways to disrupt a deliverance session. Evening is a good time especially when the household has retired to sleep.
Make sure you have soaked yourself in prayer and scripture reading before you begin. Some people may use several days fasting and praying. But don't turn up physically exhausted. Make sure you have had adequate sleep.
There are many kinds of demons, some stronger than others. Some, like Legion, as Yah'shua (Jesus) said, require "much prayer and fasting" to dislodge. Don't underestimate their power.
Those who have invited demons in by deliberate sinful behaviour usually require more time and effort than those who were victimised against their will like the victims of SRA, even if they have been forced to murder. "The spirit of rebellion is as the sin of witchcraft", Yahweh says. Those who willingly enter the occult and participate in devilish rituals of their own choice are beset by much stronger demons than those who were forced against their wills even if they both committed the same crimes.
Use a plain room for deliverance, preferably in a minister's house or in a buildiung consecrated to Yahweh like a church. Don't do deliverance in the victim's own home if you can avoid it or you may find yourself frustrated by curses and plants in the house that prevent effective ministry, unless you have first taken time to disarm these with prayer. Some satanists' houses are specially built with ritual objects embedded in the masonry that have been demonised.
Use the Divine Names of God and Christ as much as possible. Address God as Yahweh, or Yahweh-Elohim in conjunction with such words as "Heavenly Father", "Father" or "God". Address the Saviour as Yah'shua, Yeshua, or Y'shua. They are much more powerful than 'Jesus' (the Greek from) especially if it's a false 'Jesus' they have heard about and know, though if this is the only Name the victim knows the Saviour by, it will work just as well. Never use the name "Jehovah". If the victim knows only Jesus, I will use both Yah'shua and Jesus. Correct Names are important if you know them. Otherwise Yahweh is merciful and I know of plenty of successful deliverance ministers who use the Greek forms. The key power is always faith in the blood of Christ.
There is no one single formula in deliverance though certain elements are critical. Above all, it is the faith in, and love for, Christ of the one being delivered that counts together with the faith, love and discipline of the deliverance minister. Remember also that once deliverance has been effected, that this is not the end: the delivered victim needs support in terms of Christian fellowship and a sound discipling program. Too many delivered former victims are simply dumped and forgotten after deliverance which is not unlike discharging a patient from a hospital hours after having critical surgery. I have known of cases of those who have been demonised all their lives who, once healed, need to learn many basic social and even practical day-to-day living skills which we may take for granted. Stability and continuity are key elements in full recovery. Without these, a former victim may fall right back where he came from. So a stable environment is essential. In one case I was dealing with, the victim was forced to move home midway through the deliverance process by an uncaring pastor. The effect of this was to create stresses in the victim who resorted to old demonic habits in a bid to cope with the emergency. This put back the work that had been done by many months.