Toothpick thorough your hand! (in photoshop)

Step 8 Smudging

Use the smudge tool with around 55% pressure, some brush that isn't just round and try to drag the blood out a bit, so it looks like it flows down on the hand. I use long smooth motions and thinks that it gives the best results.

Open the blending options for the blood layer and use these settings:

Soon we're finished...