Leveling your sneak in the new Elder Scrolls is actually pretty easy, but just in case you don't want to waste experience on it, here's a way to steal items successfully. Don't really know if I can call this a glitch. Regardless, its effective at the same time hilarious.
I've tried it myself and it works! Bethesda is aware of this method of stealing items in Skyrim but have no intentions right now in fixing it. Understandable since there's a lot more serious issues that need their attention.
Still waiting for Patch 1.3 before continuing with my second character, need that install to reduce loading times. The install issue was fixed in the 1.2 patch but gives us an even bigger problem of magic resistance not working, so I ignored the 1.2 patch and patiently waiting for the next one. Need a break from Skyrim anyways.