"Rats" of the Verbs

Present Simple
Habits:
Always, frequently, usually, generally, often, every day
sometimes, rarely, seldom, once a week/month/year,
in the morning/afternoon/evening, at night/noon/midday
never,  ...

Present Continuous
Present: At the moment, at present, this year, now,
Future: Tonight, tomorrow, next Saturday

Present Perfect
It affects the present: Ever, never, just, yet, recently, already
It continues until the present: For, since, how long...?
Stative Verbs: Feelings and emotions.

Past Simple
Completed action: Two days ago, yesterday, last week, ...
Series of completed actions: When, then, ...

Past Continuous
Incompleted action in progress at specific time in the past: 
At 8 o'clock last night, while, as
Action in progress in the past, interrupted by another action:
____ when + (Past Simple)
Two incompleted actions in the past:
While ____ , ____

Past Perfect
A completed action which happened before another action or time in the past:
Already, by the time, before, ...

Future Simple Vs. Be + Going to
Sudden decision              Plans for the future and intentions
Predicting the future       An action which is clearly going to happen
A future timeble
Promises
Offers
Refusals
Requests
Suggestions
This evening, later, next week, soon, at ten o'clock, in the future, tomorrow, in an hour


Future Continuous
In progress at a specific time in the future:
at this time tomorrow,
by 7 o'clock,
by the end of ...,
at this time,
next...

Future Perfect
It will be completed by specific time in the future: 
By this time next week.
by ten o'clock,
by then