As I continue to repeat, the key to Scripture memory is systematic repetition.
You need a system. Begin by repeating a large number of times over a few days. Then put it on a 3*5 card for review.
Repeat, repeat, repeat. You can memorize anything if you say it enough times.
Today, let me add an additional and important detail. When you repeat it, you should say it aloud. In doing so, you will involve more of your senses and the repetition will be more memorable.
Repeating Scripture is aloud is especially helpful if you say it with emphasis and conviction. The goal is to wear a rut in your memory.
See also this post.
By way of review, here again is a copy of one of my Scripture memory sheets that shows how I keep track of repeating a verse when I am first memorizing it.