Souvent, un seul mot te dit quel temps employer :

Si tu vois…	Pense à…	Exemple
every day, usually, always	present simple	Bidu sleeps on the sofa every day.
now, right now, at the moment	present continuous	Bidu is sleeping right now.
yesterday, last week, two days ago	simple past	We arrived five days ago.
while (le décor)	past continuous	While we were walking, it started to rain.
when I was a child, back then	used to / simple past	I used to swim in the river.
tomorrow, next week, in two weeks	going to / will / present continuous	I*'m flying** home in two weeks.*