Make them understand German does not follow the English S-P-O word order. Most learning materials stick to that prerequisite much too long for the sake of building German sentences that look like English sentences. In result, many English speakers get the wrong impression German is just English with different words.
German word order in general is S-O-P. It'...
Just as we teach our children our language.
Correct short to medium length sentences, always one level above their current level.
Be strict what you say, be forgiving at their errors.
From time to time do a short lesson in grammar theory, but don't be a correcting teacher all the time.
The rest will come as time goes by.
My suggestions, in order of priority:
When you have reading material, read it out aloud. This helps with flow and will put entire phrases and sentences in your memory.
Record yourself reading out and talking. It's amazing to hear an "objective" recording versus a subjective recollection. You will find that some things like a bit slower pace of ...
Je nach Muttersprache der lernenden Person ist es sinnvoll, klare Parallelen zwischen der Grammatik in der Muttersprache und Deutsch aufzuzeigen.
Bringe der lernenden Person eine Zeitform nach der anderen bei. Beginne mit dem Präsens. Deutsch ist sehr formelhaft und es ist deshalb hilfreich, die deutschen Satzstrukturen klar aufzuzeigen ...