Practice Makes Perfect!!
Be sure you will become proficient in speaking if you practice systematically and according to a scientific procedure. But until then, you can make use of my experience:
* Never try to translate what you think in Arabic, think in English instead. In other words, you have to forget about your Arabic knowledge of language when you are talking in English.
Example: you want to say "please do the tasks simultaneously". But you cannot remember the words you need, so forget about it and tell it the way you can: "please do the things at the same time!!"
By the way, Persians like the people of Oman a lot. Did you know that?