Prayer is usually effective when combined with practical steps. Jesus was a very prayerful man but that never stopped him from actually doing the work.
Acts 10:38
How God anointed Jesus of Nazareth with the Holy Ghost and with power: WHO WENT ABOUT doing good......
This is even so with dealing with evil spirits [or demons] ;
Chapter 25 Deliverance Has a Practical Side
...After the Lord has set you free, you need to make practical adjustments, otherwise the demons will return. You need to obey the Word of God practically.
Then goeth he, and taketh with himself seven other spirits more wicked than himself, and they enter in and dwell there: and the last state of that man is worse than the first
Matthew 12:45..Demons cannot have access to Christians unless we give them a foothold. Demons keep returning because they still have access. Often, the foothold of the devil is not removed and so the demons keep returning...Without some practical steps, your deliverance from demons will never be complete.
In this book, you will find that aside prayer which is indispensable, there are a number of ways to deal with the activity of evil spirits including ; being strong in the Lord and putting on the whole armor of Christ.
Excerpt From: Dag Heward-Mills.
Demons and how to deal with them. . iBooks.