Newbie questions about how to snap modular pieces together without overlapping in Unity 5 personal.

I'm building my very first level and I'm using a free modular street kit that I found in the asset store, but I'm having a hard time snapping the pieces together without overlapping a little bit. What I did looks OK, but I guess that some built in snapping tool will do better than me. Holding control key or V key doesn't seem to work. I guess that I missed some settings somewhere. Can somebody help me with this? Thanks in advance!

 

With the object selected, hold V and then move your cursor towards a corner of the object. You should see a little box appear at a vertex near that point. Drag the object towards another object and you should see them snapping.

If the pieces are built to a uniform grid size that matches Unity's units (like my Modular Space Freighter) </shameless plug>, you can hold CMD or CTRL while moving to position the object in incremental steps.

 

http://docs.unity3d.com/Manual/UnityHotkeys.html

http://docs.unity3d.com/Manual/PositioningGameObjects.html