The evil one mainly attacks us with deceptions and temptations.
In order to not be deceived, we need to read God's word and remember it. So when the time comes and the evil one starts twisting God's word, we will not be doubtful or second guess what God has said.
We can answer the way Jesus answered when He was tested in the wilderness: "It is written..." (Matthew 4:4).
During every temptation in the wilderness, Jesus remembered what God actually said so that He defeated the evil one in every case. That's how we use the word of God as a sword against the enemy. Instead of starting to doubt God, we use the word of God by saying what God actually said and believing what God said.
It is important to work with God diligently to overcome sins.
1. Get rid of bad things in the home that might be tempting. For example, we should not watch TV or look at magazines that promote sin (e.g. pornography, bad language, scantily-dressed people, etc.). Magazines, movies, or posters that might be tempting should be thrown away.
2. We should pray for God to help us not fall into temptations. Just as Jesus said: "Pray that you may not enter into temptation" (Luke 22:40). So pray everyday for God to help you not be tempted.
3. If you do get into a situation in which you are tempted, don't go along with it. Ask the Lord for escape. Even though it might be embarrassing to talk to God when you are feeling tempted, pray to God anyway. If we ask for His help, He will not judge us. "No temptation has overtaken you but such as is common to man; and God is faithful, who will not allow you to be tempted beyond what you are able, but with the temptation will provide the way of escape also, so that you will be able to endure it." (1 Corinthians 10:13)
Just as in school or work, we give our 100%. So also in the things of God, we should give our 100%. This is what it means to love God with all our heart, mind, soul, and strength (Mark 12:33).
With 100% God's help and 100% our diligence, we can overcome any temptation. We may still fall sometimes, but keep PRACTICING and PRAYING, and God will give you a way of escape.