This is a general topic for posting any advice you have, things you've noticed that someone else may not have, or a place to ask for tips or advice. There will be a mission-related version of this topic in the Missions section if/when it is needed.
To get things started, you no longer have to visit your safehouse to save your game, as there is a 'Quick Save' option in your phone. This may have been mentioned in the phone tutorial, but I didn't notice if it was, and someone else may not have noticed it, either. A quick save saves your game, obviously, but does not advance the time by six hours like saving at a safehouse does.