How can I make my address numbers reflect & show up better?

Glow paint may do the trick.

What color is your siding? I put my numbers on a shaped board that I painted dark.

Usually Glow paint can be mixed to a range of colors blended of:

White, Pink, Green and Neon Blue

They should have color indexes that you can browse until you find a color you like.

If you don't find a color you like, put in a Solar Spotlight.

Remove the numbers and screw them on a wood plaque. Screw the plaque on the house. Address numbers will get lost directly on the house whether wood siding or brick.

https://www.hometalk.com/diy/outdoor/garden/time-to-replace-old-address-plaque-37249928

Hi Leona: I agree, glow paint may be the best for you, however, it only glows for 4 or 5 hours, depending on how much sun light the numbers get, and your numbers won't be brass coloured. If you want the brass to show, get reflective paint, you will still have brass numbers. As for keeping the paint off of your house, you can get a piece of very thin, but very stiff plastic and shove it under the numbers. You may have to paint every other, or 3rd, number, let the paint dry and then paint the ones that are unpainted later on. That way you don't smudge the wet paint. If the plastic is large enough, you can spray instead of brushing. Just don't try to rush the project. You can get the paints at most home improvement stores. Good luck.

Putting the numbers on a plaque that is colored to offer a lot of contrast is the solution I chose for a brick-front house. The busy lines of the brick made it difficult to see the number, but when the brass numbers were backed up on a plain dark-colored background, they became immediately legible.

There are companies that make house number plaques and numbers in a variety of styles and colors, and they're not that expensive. Or, as William did, make your own.