Prevent glue from oozing out of the tube
When you squeeze a tube or bottle you are increasing the pressure on the inside of the container, and the material inside the tube is forced out.  For thicker materials like glue or sealant, it takes some time and more pressure to make its way out of the tube.

For plastic bottles and tubes, when you release pressure with your hand, the container springs back to something close to the original shape and there is no more pressure in the tube.  However, with a metal tube (or similar, rigid material), the tube will attempt to keep its new shape.  The metal will continue to apply pressure to the material in the tube and the material will drip or ooze out.

The common solution is to only squeeze a small portion of the tube, and realize that the product will not come out immediately.  Squeeze a little, then wait.  However, even when you are careful, you might get more product than you wanted and trying to squeeze the sides of the tube to make the shape more of a cylinder is a good technique.  

The easiest way to "squeeze a small portion" is to squeeze from the bottom.  When you squeeze the middle, you are deforming the entire side of the tube.  When you squeeze a little at the bottom and flatten the tube as you go the pressure you apply is very localized.