Design Hack That Made Life Easy

What's one thing that makes your design workflow MUCH easier that you wish you knew earlier? I'll start first:

Using the "Isolate Selected Path" in Illustrator.

No, I'm not joking. I used to do everything manually. For example, my job requires me to design things on various dimensions and sizes (and the amount clients that DO NOT understand that PDF file IS NOT A JPEG PUT IN A PDF FILE), so the amount of small details and stacked layers I have to work with is egregious, appaling, and dreadful. What I used to do is zoomed in the fuck out of Illustrator and just constantly clicking the wrong layers. Learning the isolate function saved my life, and now I'm spamming the functionality like there's no tomorrow.

I have heard a some people mention how owning a tablet/trackpad or using Logitech MX made their designing work MUCH more easier. What's yours?