With pronunciation one of the main problems is with the bilabial plosives /p/ and /b/ which need to be explained and demonstrated to Arabic learners.
In terms of style there are a number of issues, not least of which is Arabic making less distinction between descriptive and creative writing; a scientific paper in English is purely descriptive whilst in Arabic it can be full of purple prose.
Finally there are issues where tenses in the two languages do not correspond both in meaning and usage.
There are some ideas here: Arabic - the ICAL TEFL wiki
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