The most common use for outlook is when predicting a future situation:

The outlook for the next few days is warm and humid with scattered rain showers in the north
(Weather forecast)

The economic outlook for the next quarter is not good as many believe that fuel prices will continue to rise while consumer spending is expected to remain sluggish.

It can also be used to describe someone's general view of life:
He has a very positive outlook.
i.e. he is optimistic.

When giving physical descriptions, we use the word appearance.

She wanted to change her appearance, so she dyed her hair.
He has a rather strange appearance.