[Mehrbod]

My biggest problem while writing and speaking English is to use the correct propositions. What's your recommendations how to resolve this issue?

You mean prepositions. 

You have to get the way the English mind visualizes things.
You are "at" a place, because you can't be "on" it or "in" it. In Persian you can be "in" home, but in english you can't be "in" home. Casual talk you can drop the prep and just be home as a trick in case you weren't sure.

As a matter of fact, in persian at (dar) and in (tu) are nearly interchangable, but in english there's a finer distinction, at has a touch of "separation", while "in" gives off a deeper connection. Therefore you can be in a group, you can be in the loop, and so on.

At usually goes with places, skills, etc.

"Into" has a sense of movement, it moves from something into something. That's why you peek into the mind of a genius, you're outside, then you are in. You go into the room. You jump into action, etc.

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