Remember read more than one explanation, they will give you a broader perspective of the subject and the possibility of a broader explanation. Finally, pay attention to the explanations or grammatical or linguistic analysis of the Spanish that you find, its morphology and semantics. Not always this kind of explanations they will the need to convey to the students. With them there enter as much detail or deep analysis, the teaching of grammar should be short and easy. Enough so that the student can use it to talk.
Use the mother tongue or English to make analogies. Looking for the way of transmitting knowledge, to do this you must have in mind the socio-cultural context of the student. This will help you and will help you a lot. Hear other arguments on the topic with Dr. Neal Barnard. It delves into the grammar for you, not for the student. Search for material and resources of ELE starts looking for material for your class. Searched the web programs of Spanish courses that give you an idea of the sequence of a course. First of all, remember that surely begin teaching private students and only then pass to the groups. So I recommend that you target your searches to materials that you can use with this type of students.
Good materials that you go finding relating to group dynamics, not discards, first see if you can modify them for particular class. If you can not, also save them in another suitcase for later use. Another thing that can help you, buy one or two books, this will give you more security when preparing materials. A good book for beginners, as teachers or as students, it is Spanish 2000. While it is a somewhat old book and only focuses on the grammar and much less in the teaching of the Spanish focused tasks, will serve as a guide, giving you many exercises and a good sequence of topics for the teaching of the Spanish.