Reading strategies can be organized into two distinct groups: decoding strategies and comprehension strategies.
Without getting into a long debate over whether children should learn to read through phonics or whole language, the fact is that some students need to be taught explicitly phonemic awareness. Phonemic awareness is basically being able to pronounce the bits and pieces of words to turn them into words that the student knows or has heard. Even if the word is unfamiliar, students with good phonemic awareness can usually pronounce a reasonable representation of the word. Struggling readers need to be taught the sounds of the language--the phonemes--and to be given plenty of opportunity and coaching in their use.
Some indicators that a student needs explicit instruction in phonemic awareness include: skipping words while reading, "sounding out" words incorrectly, attempting a pronunciation that doesn't make sense, and avoiding reading.
It is helpful if students are able to recognize and spell a number of simple words. Dolch vocabulary words are great for younger students. For older students, try to get a list of the 1000 most common words in the English language. Phonemic awareness starts with letter sounds. Students learn how to pronounce various combinations of letters, and they learn that letters are not always pronounced the way they should be. Consider a simple example: the word, "the," is pronounced with a short u sound. Students compare unfamiliar words with words that they know; thus the necessity for a good repertoire of sight words.
A common decoding strategy that is taught to struggling readers is called chunking. If students have developed some proficiency with phonemes, they can begin chunking unfamiliar words. Using their finger, they cover all but a chunk of the unfamiliar word. They pronounce it then move onto the next chunk. Once the student has pronounced all of the chunks, they try to put the chunks together and make it sound like a word they know or have heard. This strategy, again, requires a significant amount of practice and coaching.
One school of thought considers the ability to decode words a precursor to reading comprehension. After all, if you can't understand the individual words, how can you understand the whole sentence? Often, a struggling reader will cope with their abilities by getting answers from other students, answering the text explicit questions (e.g. "The girl's red hair blew in the breeze." What color was the girl's hair?), or making excuses for not getting their work done--avoidance behaviors.
Good readers regularly re-read, predict, infer, conclude, question, compare, contrast; and the list goes on. Good readers don't usually realize what they were doing while reading unless someone forces them to reflect on it. Struggling readers do few of the things that good readers do. They generally have only one goal in reading--to get it over with. Understanding what was read is called comprehension. Comprehension strategies are those things that a reader does to understand a text.
There is one main indicator that a student needs explicit instruction in comprehension strategies--they are good decoders, but they can't answer higher level questions about the text. Higher level questions are ones that involve more than just extracting words from the text. For example, a higher level question related to the last paragraph is, "What goals do good readers have in reading?" A reasonable answer would involve contrasting the goal that struggling readers have in reading, using the information about what good readers regularly do, and using prior knowledge or experience.
There are many comprehension strategies that can be taught to struggling readers. Telling a struggling reader to just read it again won't cut it. They need direct support, explicit instruction, a lot of practice and coaching and many opportunities to experience success. Searching the Internet for reading strategies should garner a description of at least a dozen different tried and true strategies. Following is a brief description of just a few of them.
Re-Reading - Not to be confused with "just read it again," re-reading is a deliberate attempt to find information. With the question in mind, students attempt to find relevant sections of the text to re-read. Once they zero in on a relevant section, they usually read a few sentences or paragraphs before and a few sentences or paragraphs after. Sometimes, it is necessary to re-read the entire text to get the desired information.
Predicting - Using titles, pictures, or key words, students attempt to predict the content of a text. When the student reads the text, they make comparisons to what they predicted and what they read.
Re-Stating - This strategy encourages students to look at main ideas. They re-state what they read in a shorter version. Sometimes this strategy involves restricting how long the summary can be. For example, can you re-state the description of predicting in only two words?
The best support for struggling readers is individual and intensive. In my opinion, struggling readers make the most progress when they are given one-on-one support outside of the regular classroom. Individual support allows them to receive frequent and timely feedback on their efforts. Outside of the classroom means that the support is extra-curricular and does not interfere with their regular work. If you are a parent or a teacher of a struggling reader, find out what support is available at your school. Use the terms phonemic awareness and reading comprehension strategies to communicate what your child needs. If your school can't offer the support, look for commercial services. Even though it might cost money, the benefits will be outstanding; spend the money.