"All things are difficult, before they are easy."
Future: Plans / Predictions
Plans:
Is it organised?
1) YES = PRESENT CONTINUOUS: I am flying to England tomorrow. (I have already bought tickets...)
2) NO = GOING TO: I am going to visit him in the hospital. (I just don't know when...)
Predictions?
Is there an evidence?
1) YES = GOING TO: It is going to rain tomorrow. (I have seen the weather forecast.)
2) NO = WILL: a) Spontaneous decision (I will go there.)
b) Personal opinion about the future - predictions (I think, maybe, probably, perhaps,... it could help.)
c) Indisputable facts (I will be 42 next year.)
d) Offers / request for help (I will help you.)
e) Strong promises / expressions of determination (I will make it.)
f) Order / imperativ (You will tidy the room.)
Statements about events based on present facts, and when these facts are something fixed like a time-table, schedule, calendar.
PRESENT SIMPLE: The plane arrives at 18.00 tomorrow.
How to express future: https://en.islcollective.com/video-lessons/future-tenses-english