The sign for "hug" can either use the "A" handshapes, like I do below, or you can grab onto the upper arms with "curved hands."
HUG:
A double movement tends to be the noun form of "a hug" or it can mean the process of "hugging."
A single movement tends to be the verb form of "give a hug." You might see some people twist the torso a bit for emphasis, but I wouldn't unless I wanted to describe an extended (long) hug.
HUG:
Note: Deaf people hug more than Hearing people do. It's a cultural thing.
Also see: LOVE
Notes: