Please share your research with us.
First of all,we need to respect the minorities by using their language and ling English with their language.However,we cannot use their language to teach English,but we can only teach them English in English,because they need to learn English,not reviewing their own language.
If they have a language that uses alphabets or letters,take full advantage of that language.We need to remember that most of the learners whose mother tongue cannot learn English well is due to the fact that Chinese and English are not related,both have no relation whatsoever.
For minorities to learn English well,they have to start with their alphabetic language,if they have one,then,very quickly,they need to forget their own language and start to learn everything,I mean everything,in English.
Never translate.If they want to learn English,it is English only.Never translate English,anything,into the mother tongue.It is even worse to translate their mother tongue into English since they will be using English to talk their mother tongue.That is the worst,exactly like the English many of the native Chinese speakers are using.
Choose a textbook that has only English in it.Choose a dictionary that has only English in it.If we really want to help the minorities to learn English,ask them to forget their mother tongue when they are learning English.They can translate when their English is up to the level of their mother tongue.If their English is much worse than their mother tongue,never translate.
The only motto they should,or any English language learner should,remember,is,never use English to review your mother tongue.
Use your mother tongue to learn your mother tongue,but only use English to learn English,never mix it up with your mother tongue.
Good luck.