Style guides sound like something reserved for big companies with design teams, but a stripped-down, one-page version is genuinely useful even if it's just you designing everything — mostly because it saves you from re-deciding the same small things every single time you sit down to make something new.
The simplest version covers four things: your core color palette (2-4 hex codes you actually reuse, not an infinite rainbow of options), your typography choices (one display font for headers/titles, one body font, and that's genuinely enough for most small shops), a linework or illustration style note (bold outlines vs. fine detail, flat color vs. shading — whatever your actual habit already is, just written down), and a short list of recurring motifs or symbols that feel "yours" within your niche.
Writing this down does two concrete things. First, it speeds up every future design decision, because you're not relitigating your color palette from scratch each time — you already know your three go-to colors and just pick from them. Second, and this matters more than it sounds, it makes it much easier to notice when a new design idea doesn't actually fit your brand, before you've spent hours building it out. That's a much cheaper mistake to catch on paper than after publishing.
You don't need fancy software for this — a single page in Canva, a simple Google Doc, or even a physical page pinned above your desk works fine. The goal isn't a polished, presentation-ready document; it's a quick reference that keeps you consistent without having to hold every past decision in your head.
If you're not sure what your existing style guide already is, work backward from your best-performing designs rather than starting from a blank page — pull the actual colors, fonts, and stylistic habits from the pieces that are already working, and write those down as your baseline going forward. You're not inventing a brand from scratch; you're just naming the patterns that are already there.