Spiritual Roadblocks: The most common blockages
Not willing or ready - As elementary as this sounds, many deliverances are unsuccessful because the person was not ready or willing to be truly delivered. They were merely looking for a quick fix for their problem, and were not willing to take the necessary steps to receive and maintain their deliverance.
Unforgiveness - Bitterness is a very popular source of spiritual defilement (Hebrews 12:14). If you don't forgive others, God will not forgive you (Matthew 6:15). Unforgiveness puts us in the hands of tormenters (Matthew 18:23-35), which are demonic spirits.
Strongholds - Strongholds are incorrect thinking patterns in our minds that we see things through. Many people see themselves as failures, so they feel like failures. Others see God as a cruel and dictating taskmaster, which causes them to feel distant and unloved by their heavenly Father. If you have a hard time feeling God's love, you can cast out all the demons in the world, but if you don't see God as a loving God who loves you, it's going to be very difficult to feel and receive His love.
Unconfessed sins - If we confess and repent of our sins, God is faithful and just to forgive us (1 John 1:9). But if we choose rather to keep our sins hidden and to ourselves, we cannot expect God's forgiveness. There is also power in confessing our faults to one another, as James 5:16 tells us, "Confess your faults one to another, and pray one for another, that ye may be healed. The effectual fervent prayer of a righteous man availeth much."
Soul ties - Having a soul tie with somebody means your soul is joined with theirs (1 Corinthians 6:16). Being joined to another person with an unclean soul tie can allow the transference of spirits and bondage between the persons. It is vital to break of all bad soul ties from unhealthy past relationships so that the enemy cannot use them against us.
Cursed objects - The Bible gives us a clear pattern of destroying false gods, idols, and so-called cursed objects. God warns us that bringing a cursed object into our home can bring a curse upon us as well (Deuteronomy 7:26).
Lack of faith - Not understanding or believing God's will or the truth about your situation can keep you in bondage as well. If you don't realize the authority and freedom you have in Christ, it can be very hard to walk in it and eat of it's fruit. Knowledge of the truth is indeed an important tool in our spiritual toolkit.
Un-renounced vows - Vows and oaths bind the soul (Numbers 30:2). The way to break free from any ungodly vows is to repent of it and renounce it verbally in Jesus' name.
Unbroken curses - Both ancestral curses and curses encountered in one's own life must be broken. I believe ancestral sin curses are automatically broken so long as we have accepted Christ, and do not take part in our ancestor's wickedness, but other types of curses must be broken before complete deliverance can be obtained and kept.
Residing spirits - Demons often need to be cast out of a person before they are able to fully overcome many persistent bondages. Demons are often found behind many issues such as fear, depression, physical infirmities (arthritis, cancer, deafness, etc.), mental illnesses, etc. and need to be driven out as Jesus and the early church went about doing.