Changelists, Tasks, Branches – when to use what?

I'm using PhpStrom for 6 months now and still haven't used all features. I just discovered Tasks (with Trello integration, very cool!).

I am wondering when do I use changelists, when creating a Task (with a changelist connected?) and whether to create a new git branch or not. I do not work inside a team, but I often need to work on multiple tasks within a project. And sometimes different tasks required to work on the same file. And more often completing a task takes a couple of weeks … a lot longer I can keep things in my mind :-)

So I always ask myself should I just create a new changelist to keep track of my edits or create a new branch. How do you decide? Is this more of a personal favour or do you have some criteria what to do?

Coming from Atom all of this is quite new to me :-)