Here is a short version of the main points on how to protect your faith:
Faith will Desire God's Word and Experience God through Scripture
The Word of God - I Peter 2:1-3 - Develop an appetite for God's Word that is like that of a newborn babe (Matthew 4:1-4).
The Spirit of God - Romans 8:8-18 - Develop a working relationship with God's indwelling Spirit, so that you operate with His power and perspective (Galatians 2:20).
The Son of God - Romans 16:25-27 - Develop a Christ-centered / Gospel-centered approach to your study of God's word. Progress from milk to solid food (Hebrews 5:8 - 6:3).
The Grace of God - II Peter 1:2-11 - Develop the disciplines that should accompany a strong growing faith. Make sure that your knowledge & faith are fruitful (II Timothy 2:1-7).
Details for II Peter 1:2-11 - As you cooperate with God and apply yourself to the Scriptures and seek to build your faith, you will experience the grace of God ministering to you - confirming you, strengthening you, and protecting you. See John 10:27-29; I Corinthians 1:3-9; Ephesians 3:14-21; Colossians 2:6-10; Jude 1:20-21; I Thessalonians 5:16-24; James 4:6, 8a, 10; II Timothy 4:18.
Note for II Peter 1:5 & 11
II Peter 1:5 says that we should add to our faith - supply/supplement our faith. There is a Greek word used, here, that means "To supply lavishly." The same Greek word is used again in II Peter 1:11. Here it tells us that God will minister/supply/provide an entrance into His heavenly kingdom with welcome and reward.
Summary: If you take gospel knowledge, with its exceeding great and precious promises, found in God's word (II Peter 1:2-4) and add to your faith those things that are listed in II Peter 1:5-7, you will be able to make sure of your true relationship with God and also be sure of rich reward in heaven (II Peter 1:8-11). See II Corinthians 13:5.
See Matthew 6:19-21; 13:1-9,18-23; John 13:12-17; 15:1-8; I Corinthians 3:11-15; Ephesians 2:8-10; II Timothy 4:6-8; Titus 3:5-8; Hebrews 6:7-12; James 1:12,21-27; II John 1:8; Revelation 14:13.