[header] How to pick up a pet mouse [title] Grasp your mouse's tail gently to restrain it. [step] To keep your mouse from scurrying away while you try to pick it up, grab the center or base of its tail with your thumb and index finger. Mice tails are quite fragile, so your grip should be just firm enough to keep your pet from scampering off. 
[substeps] Do not, under any circumstance, pick your mouse up by its tail. Doing so will cause your pet lots of discomfort and, in some cases, can lead to major injuries like degloving.