Planning a kitchen backsplash tiling: common mistakes and pro tips

[Kyle.L]

I'm planning to retile the backsplash in my kitchen this weekend, and while I've watched a dozen tutorials, I'm nervous about getting the mortar consistency right and ensuring the cuts around the outlets are clean. I have a basic tile cutter and all the materials, but this is my first tiling project beyond a simple floor. For experienced DIYers, what are the most common mistakes beginners make with a project like this, and what specific tips or tools made the biggest difference in achieving a professional-looking result on your first major tiling job?