The Four Spiritual Laws
If you've gone through a discussion with someone and you want to present the gospel message in a simple and systematic way, the well known "Four Spiritual Laws" can be of help. They are simple, to the point, and use Scripture to convict, convince, and convert. They are:
The Roman Road
Another list of verses usable in the same way as the Four Spiritual Laws is the "Roman Road." The advantage to these seven verses is that they are all in the book of Romans. Sometimes this is an advantage when you don't want to flip through a lot of pages.
Rom. 3:10, "As it is written, 'There is none righteous, not even one...'"
Rom. 3:23, "For all have sinned and fall short of the glory of God."
Rom. 5:12, "Therefore, just as through one man sin entered into the world, and death through sin, and so death spread to all men, because all sinned."
Rom. 6:23, "For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord."
Rom. 5:8, "But God demonstrates His own love toward us, in that while we were yet sinners, Christ died for us."
Rom. 10:9-10, "if you confess with your mouth Jesus as Lord, and believe in your heart that God raised Him from the dead, you shall be saved; for with the heart man believes, resulting in righteousness, and with the mouth he confesses, resulting in salvation."
Rom. 10:13, "For whoever will call upon the name of the Lord will be saved."
I recommend you put the Roman Road in your Bible. Go to Romans 3:10 underline it and write Romans 3:23 next to it. Then go to Romans 3:28, underline it and write Romans 5:12 next to it, and so on. That way all you need to do is memorize where you start: Romans 3:10.