I am a big believer in textbooks. Find an affordable textbook that matches your material reasonably well. One way to ensure affordability is to choose a textbook that is one or two editions old. There are some classics that can be bought for $0.01 plus shipping. Make sure the library has several copies for check-out and a couple for use in the library only ("on reserve").
Create a simple blog where you post basic information for each lecture, stating what portion of the textbook will be (or was) covered, any additional notes that are not in the textbook, and what the homework assignment is. By this means, you will be making it easier for students who have missed a class to keep up.
Let your students know that your office hours are such-and-so or by appointment. Schedule your office hours at a couple of different times. For example, don't schedule them on Tuesdays and Thursdays at the same time.
Encourage the students to help each other. There are a number of ways of doing this. For example, assign a small group project early in the semester. Allow students to form their own small groups, but also assign groupings to those students who have not formed their own. This will encourage the formation of student groups. Also, if a large number of your students come to office hours, you can ask one of the stronger students to work with a small group of students. This delegating wouldn't just give you a break, and wouldn't just enable you to get more students serviced during your office hours; it would also help the students who are in the helping role. They will solidify what they learned; and they will gain experience in teaching and tutoring.
You might also want to organize a walk-in tutoring service on campus.
It is through your efforts, and the efforts of other dedicated professors, that the educational system in your country will improve. You are helping hundreds of today's students to achieve greater rigor. When the best of them are teaching and continuing in your footsteps, they in turn will also reach hundreds of students.
You have to start somewhere. Hopefully, at some point in your lifetime, your university will figure out how to schedule the extracurriculars in such a way as not to interfere with attendance at lectures and labs.
The university I attended in Mexico was so disorganized, at least a third of our classes were canceled, with no advance notice, because of an instructor just not showing up. So -- things could be worse!