Start out with a bang!
Starting a session "hanging out" or chatting is problematic. Often by the time players get into the game, the session is over. One solution is to start with action.
Consider ending the previous session just before some action starts. If you're starting something new, just give a handful of sentences setting things up, then into the fray!
Consider starting "in medias res", in the middle of the action. "Welcome to the session. Everyone got your new characters? Here's the situation: you were smuggling Death Star plans for Princess Leia. Stormtroopers have tracked you down. Now you're pinned down behind crates in the Mos Eisley spaceport. Roll for initiative!"
Starting out with a bang is even more important for one shot games and first games. In the absence of prior connection to your character, you've got nothing to work with. Sure, you've got a background, but chatting about something you cooked up on your own is boring. Simply having the characters hang out and chat wastes time. Real character is revealed in their actions, not their history. Let the players leap into action.