Bible memorization is always time well spent. All Scripture memory is "profitable for teaching, for reproof, for correction, and for training in righteousness" (2 Timothy 3:16). And especially useful are one-verse statements of the gospel.
When you memorize a "gospel verse," and keep it warm, you have hidden in your heart a divinely inspired and inerrant expression, in human language, of the very point of the whole Bible and all of history. You carry with you the sword of the Spirit in its strongest alloy. One-sentence encapsulations of the Bible's central message strengthen our spiritual backbone and solidify our core, rooting us deep down in the bedrock of God's heart and confident combat with unbelief, whether our own or someone's else. Gospel verses are invaluable in both evangelism and discipleship.
So, alongside other Scripture memorization efforts, sprinkle in some gospel verses that guide and shape and flavor your whole reservoir. By "gospel verses," I have in mind verses like John 3:16 (don't begrudge this verse its fame-it's for good reason), verses that communicate succinctly that Jesus saves sinners.
Here's a starter list of ten. Perhaps keep your eyes peeled for others and add them as you go-and don't be surprised if you find a lot in Romans:
For even the Son of Man came not to be served but to serve, and to give his life as a ransom for many (Mark 10:45)
God shows his love for us in that while we were still sinners, Christ died for us (Romans 5:8)
For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord (Romans 6:23)
There is therefore now no condemnation for those who are in Christ Jesus (Romans 8:1)
He who did not spare his own Son but gave him up for us all, how will he not also with him graciously give us all things? (Romans 8:32)
For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God (2 Corinthians 5:21)
For you know the grace of our Lord Jesus Christ, that though he was rich, yet for your sake he became poor, so that you by his poverty might become rich (2 Corinthians 8:9)
The saying is trustworthy and deserving of full acceptance, that Christ Jesus came into the world to save sinners, of whom I am the foremost (1 Timothy 1:15)
In this is love, not that we have loved God but that he loved us and sent his Son to be the propitiation for our sins (1 John 4:10)
Worthy are you to take the scroll
and to open its seals,
for you were slain, and by your blood you ransomed people for God
from every tribe and language and people and nation (Revelation 5:9)
Adapted from Habits of Grace by David Mathis