Skip if you already know this — apparently it's been around for awhile and I had no clue.
You can drag an open texture preview onto any applicable surface, whether it's a prim face or a profile picture.
This may be a quick shortcut if you've already got a texture open and were under the assumption (like me) that you had to drag it from the PICK: TEXTURE window or from your inventory.
What's a Second Life trick that you wish you discovered earlier, because it seems totally obvious in hindsight?
(Don't be shy, there's always something new to discover in Second Life, and I encourage this curiosity! The only wrong answer is not learning.)