My personal strategies for bringing my personal artistic voice to bear, front and center, in my work are still evolving but there's one thing I've been doing for years: carefully considering the type of imagery I shop for.
I avoid images and supplies that are overly pre-determined. By this I mean that I don't buy stuff that already has a strong narrative or style that tells its own story. For example, I try not to purchase rubber stamps that are connected with a specific artist's name. I'd rather not have someone look at my art and squeal "Oooh! I just love that Tim Holtz stamp!" If you think I'm going to slam Mr. Holtz and the supply empire he's built, you'd be wrong. There's a ton of stuff in the Holtz line-up that I adore. Do I own some of his stamps? You bet. Some of his older clear stamp sets are awesome for journaling. But I use those images super sparingly and I don't make them the focal point. Generally speaking, I stick with neutral, universal imagery like non-descript text, basic shapes, things that can blend into my work and help tell my story. And by sticking with a narrow range of imagery, I increase the odds that my work will feel like a cohesive whole. (Remember: Repetition is one of your best friends.)
Of the best way to have tools and images that serve your narrative needs is to make your own: cut your own stencils, carve your own stamps, draw (or digitally create) your own images...the less you can rely on commercial imagery, the more your art shines with your personal voice. However, it isn't always practical or possible to make it yourself and let's face it, there's some cool stuff out there! But by choosing carefully, you can save some money and build a stash that doesn't simply sit around and dominate your mental and physical space.