The Bible teaches, and the Church of God has long taught, that we should examine ourselves before Passover in order to take the Passover in a worthy manner.
"Therefore whoever eats this bread or drinks this cup of the Lord in an unworthy manner will be guilty of the body and blood of the Lord. But let a man examine himself, and so let him eat of the bread and drink of the cup. For he who eats and drinks in an unworthy manner eats and drinks judgment to himself, not discerning the Lord’s body. For this reason many are weak and sick among you, and many sleep. For if we would judge ourselves, we would not be judged. But when we are judged, we are chastened by the Lord, that we may not be condemned with the world" (1 Corinthians 11:27-32).
Also, "Examine yourselves as to whether you are in the faith. Test yourselves. Do you not know yourselves, that Jesus Christ is in you? - unless indeed you are disqualified. But I trust that you will know that we are not disqualified" (2 Corinthians 13:5-6).
To examine ourselves, we need to meditate (think about, reflect) on where we fall short of obedience to God and His way of life. This helps us to see why Christ had to pay the penalty for our sins, and it helps us to see where we need to work to improve. We need to measure ourselves by God's law and God's word.
A good way to examine ourselves is by God's word, the Bible.
"For the word of God is living and powerful, and sharper than any two-edged sword, piercing even to the division of soul and spirit, and of joints and marrow, and is a discerner of the thoughts and intents of the heart" (Hebrews 4:12).
Here are some scriptural passages I use and may be useful to others as a starting point. You can use these and add to them passages that help you in particular.
LOVE
God is love (1 John 4:8).
Love is the fulfillment of the law (Romans 13:10).
Love chapter (1 Corinthians 13:1-13).
TWO GREAT COMMANDMENTS
Love towards God (Deuteronomy 6:5, Deuteronomy 11:1, Matthew 22:36-38, Mark 12:29-30, Luke 10:25-28).
Love towards neighbor (Leviticus 19:18, Matthew 19:16-19, Matthew 22:36-40, Mark 12:28-34, Luke 10:25-28, Romans 13:8-10, Galatians 5:14, James 2:8-13).
Parable of the good Samaritan (Luke 10:30-37).
THREE WEIGHTIER MATTERS OF THE LAW
Weighier matters of the law, justice, mercy, and faith (Matthew 23:23).
TEN COMMANDMENTS
Exodus (Exodus 20:1-17).
Deuteronomy (Deuteronomy 5:5-22).
SERMON ON THE MOUNT
Matthew (Matthew 5:1-48, 6:1-34, 7:1-29).
Luke (Luke 6:20-49, 11:1-13, 12:1-12, 22-53, 13:23-30).
MESSAGES TO THE SEVEN CHURCHES
Ephesus (Revelation 2:1-7).
Smyrna (Revelation 2:8-11).
Pergamos (Revelation 2:12-17).
Thyatira (Revelation 2:18-29).
Sardis (Revelation 3:1-6).
Philadelphia (Revelation 3:7-13).
Laodicea (Revelation 3:14-22).
WARNING ISRAEL AND THE WORLD
Ezekial warning (Ezekiel 3:17-21, 33:1-20).
Hold back those stumbling to the slaughter (Proverbs 24:11-12).
MISCELLANEOUS
Here are a few more that help me.
Bring every thought into captivity to the obedience of Christ (2 Corinthians 10:4-6).
Whatever is good, think on that (Philippians 4:8).
Be a living sacrifice (Romans 12:1-2).
Trust in God (Proverbs 3:5-6. Jeremiah 17:7-8).
Trust not in man (Psalm 146:3-4, Jeremiah 17:5-6).
Overcome Satan with prayer and fasting (Leviticus 23:27-32, Leviticus 16:20-26, 29-34, Revelation 20:1-3, Matthew 4:1-11, Luke 4:1-13, Matthew 17:14-21, Mark 9:17-29).
Avoid violence in entertainment (Isaiah 33:14-16).
Humility (Luke 18:9-14, James 4:5-10).