One easy rule of thumb: when you're deciding which starches (rice, wheat, corn, potatoes, etc.) are OK, just don't eat white food. No sugar, no white flour, no white rice, no white potatoes. Take it one step further: don't eat anything that comes from a box or requires you to shout into a microphone in the drive-through. Ignore Joe with his endless love for crap-in-a-box cereal. (I love Joe, but I have no idea how he is alive with what he eats.)
Cook from scratch at home. Minimize baked foods like biscuits, bread, cake, which are generally simple carbs. (Sneak in some cornbread; I won't tell.) Instead, load up on cooked and raw veggies, which are generally complex carbs: snap peas, green beans, asparagus, Brussels sprouts, broccoli, spinach, kale (yuck), corn on the cob up to a point. You want to eat food that your body has to work to digest (= complex carbs), instead of that straight-shot-to-your-bloodstream stuff like cinnamon buns and other "white stuff" food (= simple carbs.)
I'm flirting with a pre-diabetes diagnosis courtesy of fasting blood glucose of 108, although my HgbA1C is still OK, and I just got preached at by my doc this morning, lol. So I'm rooting for you! I don't want to go on metformin either. Poopies or no poopies. I know that at this point, I can control this and improve my health, and I will.