For a future possibility that we don't have evidence for
will
For future plans which are already arranged or fixed
present continuous
I am going to start looking for a new flat next week.
be going to
The cleaner is coming tomorrow afternoon at 3 p.m.
present continuous
We might move to a bigger city when the children are older
might / future prediction we can't be sure of
For things we want or intend to do in the future but haven't made definite arrangements yet
be going to
My exams start on Tuesday 3rd of June.
present simple
Jhon has already painted 3 walls, so I think he is going to finish the room soon
be going to / there is evidence for the prediction in the present situation
For future predictions we can't be sure of
might
For future events that have a timetable
present simple
There is evidence for the prediction in the present situation
be going to
I think the shop will probably deliver the fridge next week
will / a future possibility that we don't have evidence for