Do you have any tool that you use all the time? Do you recommend it to everyone unprompted? Is it ridiculously specific to your situation, wants and needs? Let every one know how they can make their sewing better!!
I myself don’t have any at the moment, but I have been eyeing a nice pair of left-handed fabrid scissors for quite some time and I might get it some day.
Now that I think about it: scissor sharpeners!! I have one that I use regularly on my basic scissors ans I feel like it makes a noticeable difference. (I currently use an all purpose Fiskars that is dedicated to fabric and it’s neither good nor terrible)