Instinctively, most people try to peel the backing away from the sticker. The trick is to do the exact opposite - you need to peel the sticker away from the backing!
Follow these steps for excellent success:
1. Hold the sticker "front side up" (design facing you) and pick a prominent corner.
2. Use your finger nail (or friction from your finger pad) to peel the sticker away from the backing (see the GIF below)
3. If you continue to have any difficulty, I can highly recommend this youtube video which will walk you through the process.