I haven't taught at school, but I have taught many reading courses at the university level.
Before talking about the main problems in reading, I may share with you some surprising distractors that prevent the students from learning:
1-Students at the university are over-obsessed with the "mark" or "grade" that they may get in their exams. This distractor prevents them even from undersrtanding that it is only when they learn that they can get a higher mark.
2-It is noticed that some students are not interested at all in learning. Some of them just go to the university because their parents want them to get a university degree.
3-Reading can only be improved when a student reads and reads and reads. Our students do not read a lot.
4-Reading requires one to be able to know how to pronounce a word. Now imagine a student who does not know how to pronounce a word. How would he be able to read a text or a passage? He wouls stutter a lot while reading the passage.
The above problems vary in size from one university to another but they really have very adverse effects on the teaching process. I called them distractors because they are not directly related to reading problems
Anyways, for your purposes, you may need to consider the following two points whenever you deal with ELS reading classes:
When we teach reading, we make sure that our students would be able to solve problems related to the following VERY SPECIFIC SKILLS. This means that almost all exercises must focus on improving these skills.
A- Thinking of the text:
When you teach students a reading passage about Edison, for example. It would be a good idea to discuss with them teh benefits of lamps and audio recording machines. This will preapre them to the reading lesson before they read it. It is VERY VERY IMPORTANT that the reader would know something about what he/she is reading. This is very helpful in understanding a text even if there are difficult words.
B- Main ideas:
Let a student scann the text and tell you what the main idea is about.
Here we have a big problem. If our passage is about Edison who invented lamps that work through electricity, for example. Some students will erroneously assume that the main idea is about: lamps. Others will say it is about electricity!
How to solve this problem?
You have first of all to be able to have prepared your students well to the passage before reading it by discussing the main idea with them. Always focus on the main idea in your discussion so that they do not miss it. Repeat it through questions many times so that they are obsessed with it.
ESL students typically suffer from determining the main idea as they either choose a NARROW idea or a BROAD idea. I wouls therefore strongly advise you to read books on the TOEFL as these books explain in details how to solve this problem.
C- Specific Details:
Ask direct questions that have clear answers in the passage and see whether they can find the answers or not. Some questions might be difficult, others might be easy. Please refer to TOEFL iBT books and tutorials. They are veeeeeeeeery important and informative.
D- Difficult words:
You must teach students how to understand the text even if there happen to be difficult words. You have also to let them use their own strategies in figuring our the meanings of difficult or new words.
The dictioanries are important. Using a dictioanry is a very good habit, but students must also know that an English-English dictioanry is very important if they want to understand how a word, a phrase or an idiom is actually used.
Ask students to tell you what the pronouns "he", "one", "this" refer to. This is an important exericse that will enable the student to establish cohesion/coherence in the text.
If we say: They are crying because she has decided to leave them.
it would be logical to say that "they" love "her". This piece of infroamtion is not directly provided in the sentence. Yet, it can be "inferred".
Again, I strongly recommend that you resort to TOEFL books and tutorials. They are very very informative on the matter.
2. Students' Background
It is very important to notice that some passages present certain cultural hints that do not exist in the students' culture. Pay attention to them and try to solve such problems.
3.Problems in grammar
My students used to suffer when reading English texts because the English grammar is totally different from the Arabic grammar. Their lack of understanding of the English verb system for example resulted in them committing serious mistakes in reading a passage. Be careful however! Talk about grammar ONLY when it is important to let them udnerstand the meaning of the text from a grammatical point of view; and never change the reading classroom into a grammar lesson.
I hope these remarks are helpful. If you need any clarification, please let me know.