"to look", "to see" or "to watch"

to look     to pay attention; to try to see what is there; seem
[Cambridge Advanced Learner's Dictionary]

phrasal verbs
look back - to think about something that happened in the past
          When I look back I can see where we went wrong.          Kiedy patrzę wstecz, widzę co poszło źle. 

look in - to visit a person for a short time, usually when you are on your way somewhere else
          Can you look in on the kids before you go to bed?          Możesz zerknąć na dzieci zanim pójdziesz spać?

look out - said or shouted in order to tell someone that they are in danger
          Look out! There's a car coming!          Uważaj! Samochód nadjeżdża!

look up - to become better
          I hope things will start to look up in the new year.          Mam nadzieję, że w nowym roku wszystko będzie lepsze.

COMMON MISTAKE
look at
When "look" has an object, the correct preposition to use is "at". Do not say "looking something", say "looking at something".
          She looks at the photo on her desk and smiled.          Ona spoglądała na zdjęcie na biurku i się uśmiechała. 

look forward to
When "look forward to" is followed by a verb, that verb should be in the "-ing" form. Do not say "look forward to do something", say "look forward to doing something".
          I look forward to meeting you at the conference.          Z niecierpliwością czekam na spotkanie z Państwem na konferencji. 



to see     visual impression come to eyes; understand
[Cambridge Advanced Learner's Dictionary]

phrasal verbs
see sth out - to wait or last until the end of a difficult event or situation
          They saw out the storm in the best shelter they could find.         Schronili się w najlepszym miejscu jakie mogli znaleźć podczas burzy. 

see sb off - to send to the place that someone is leaving from in order to say goodbye to them
          My parents saw me off at the airport.           Moi rodzice odwieźli mnie na lotnisko. 


to watch      to look at something for a period of time, especially something that is changing or moving
[Cambridge Advanced Learner's Dictionary]

phrasal verbs
watch out - used to warn someone of danger or an accident that seems likely to happen
          Watch out for thieves round here.          Uważaj tutaj na złodziei.

watch over sb - to protect someone and make certain that they are safe
          The prince has two bodyguards watching over him every hour of the day.          Książę ma dwóch ochroniarzy, którzy pilnuja go w ciągu każdej godziny podczas dnia.