I would begin by providing a list of the forms you want to teach (from their journals). I would use three principles in teaching the forms: 1 Context -- provide enough context to give the meaning; 2 Contrast/Variation - give examples which contrast the meaning, even if they don't exist in the journals; 3 More is better -- the more forms you teach them, the more they will remember and use.
If you send me a list, I can compare them to the DMs we have found among bilinguals, people with aphasia, etc.
I agree with Joel Walters that using context is the best way to teach conjunctions besides asking learners to use in real dialogues inside class or outside to be sure that they use them appropriately and give feedback about that to their colleges
Do you distinguish between conjunctions proper and other DMs, e. g. particles or adverbials? The latter may have the same semantic functions but different syntactic properties, e. g. their position in a clause is not necessarily at the beginning (сf. "but" and still"). I have no practice in EFL, but I would recommend some theoretic exposition to students about there being semantic relations among sentenses' meaning (examples e.g. from Rhetorical Structure Theory) and special lexical means to express them.
The only addition to these comments I would add is to show counter examples or potential errors the learners could make. I would consult Rod Ellis' work on how to approach grammar instruction. It is important that students are allowed to experience a rule-generation process, practice the structure, and ultimately, master it. Below I have a link to one of his publications that details (what I find to be) the most balanced approach to grammar: