To me the hardest thing in English is preposition and i make mistakes here. Fore example i confuse: "it is difficult for me" and "it is difficult to me"
Is there any rule?
The prepositions "to" and "for" are often interchangeable. In this case the preference is "for", and the preposition "for" conveys an idea of advantage/disadvantage.
You could say, "It is difficult for me," or, "It seems difficult to me." The preposition "for" shows involvement, while the preposition "to" conveys a perception.
"It is difficult to read in a moving vehicle, at least it is difficult for me."
When preceding a verb, use "difficult to". When preceding a noun, use "difficult for".
I'm also confused in many cases by how to use prepositions. I guess a good way to understand these subtle differences, as in your example, is to read more. At some point you will naturally feel the differences like native speakers do. At least that's what I'm trying to do. I don't think most native speakers actually pay attention to the explanation of these differences, they just feel it right or wrong.
As for your example, I think "for" sounds better. You could also add "to" after it, like:
"to" only makes sense if you say:
When to use "to" and when "for"? has some good tips.
Just my two cents. Take my suggestions cautiously, since English is my second language as well. :)