I hope I’m understanding your question. The major system provides the clues. If you see “52”, the first step is to convert the digits into the consonant sounds: “L” and “N”. Then try to think of the word that has L and N as the first two consonants. With a bit of review, it should lead you to the image of the LioN.
Then go to the next number, 53. The sounds are “L” and “M”. That might lead you to the word LeMon. So you can picture a lemon.
Then go to 54. The sounds are “L” and “R”. Maybe the image is LaRd, a fishing LuRe, or someone name LauRa. You can pick any image that fits and is memorable.
Keep reviewing the numbers from 0-9 and 00-99 making notes of the ones that you miss. You can practice those more often and/or change the images to make them more memorable.
If you haven’t seen it yet, you might also be interested in this post: How do I memorize a mnemonic number or card system?
You can pick images based on the shape. A + sign might be a cross or a telephone pole. A - could be a plank of wood, stick, dart, arrow, or pencil. * could be a star in the sky, a star sticker, a caltrop, naval mine, shuriken, or anything with that general shape that comes to mind.