From Christianity.com: 

1. He plants doubts and lies (Gen. 3)
2. He fights against your faith (Eph. 6:12)
3. He will tempt you with sexual immorality (1 Cor. 7:5)
4. He will try to cause disunity amongst Christians (Mt. 13:38-39; 2 Cor. 11:13-15)
5. He will slander you before God (Rev. 12:10)
6. He will try to take you down through pride (1 Pet. 5:6-8)
7. He will persecute you for your faith (Rev. 2:10)
8. He will try to cripple your faith through fear (2 Cor. 4:8-9)
9. He will try to sidetrack you with worldly things (1 John 2:15-16)

Click here for further explanation of each point.