going to
This way you can express a personal intention or make a prediction about what you know/feel/see as in these sentences:
I am going to stop smoking this year. The sea is going to be very rough this afternoon, so don't go swimming.

Future Simple
Back to "will" and "shall". With these two words plus the infinitive of a verb you can express: a future fact, a sudden decision, an offer, a threat, a promise, an opinion about the future, a probability especially after think, suppose, expect, doubt if.

Here are a few examples:

Tomorrow will be my birthday.
It's all right I'll get the shopping.
I will take you in the car if you like.
I'll stand by you whatever happens.
I suppose we'll manage without the car.

Present Continuous
This is almost the same as "going to" but it's not quite as personal. Look at this:

The Government is thinking about introducing a new law.

Present Simple
We use this when we are thinking of the certain future, something already arranged as in a timetable or programme:
Your train leaves in ten minutes.

Is to/Are to
These are used to express an instruction or something arranged officially. Here is an example:

The finance ministers are to meet next month to discuss the crisis.

About to/Due to
We use these when we want to describe actions that are expected to happen, usually fairly soon. An example:

The 100 metre race is about to start any minute now.

Below you can see a story I've written using some highlighted examples of how you can express the future.