“ESL Learner” defends the use of the dictionary in a comment here. Of course we need a dictionary but the less time we spend in the dictionary the better. We should read on line and use on line dictionaries like Babylon and Kingsoft. In this way we get instant explanations and translations. When reading away from the computer I simply let the unknown words go by me. Traditional dictionaries are simply too time consuming and inefficient.
But even the on line the dictionary is not enough. We need to create a dynamic database of our new words and phrases linked to real examples of these words in use from our reading and listening. The dictionary examples are not real. We need to learn from real context.
Dictionaries provide guides to pronunciation often using the phonetic alphabet. This can be a help if the learner knows the international phonetic alphabet. I have learned 10 languages and never bothered learning the IPA. To me it is just one more artificial obstacle between me and the language. The spelling of the language I am learning has to link up with the sound of the word in use. The IPA like grammar explanations is just a distraction.
I spent most of time listening over and over to the content I was learning from. I developed my pronunciation skills by repeatedly listening to interesting content. Then when I read that content I would pronounce these words to myself. Occasionally I would read the texts out loud.
The point is that whenever you take your learning away from real context, as in when you are studying the dictionary, you are taking time away from the most efficient activities, reading, listening and speaking. You will learn to be fluent by training your brain, not by trying to understand or deliberately gain knowledge.