Annotating is not only choosing main ideas and looking up words you don’t know.
That is important, but it’s not everything. By the way, I recommend using a thesaurus instead of a dictionary. It gives synonyms instead of definitions – if you can get a combination of both, that is the best. You should also write some interesting questions about the article, and VERY IMPORTANTLY, write in your reactions to the topic, and your stories/examples. You need to develop your response to what you read, not only analyze what you read.
VERY IMPORTANT. Finding the main ideas is preparing for the summary. Thinking about what you are reading and writing down your thoughts/ideas/reactions is preparing for the essay. You must do both.
When annotating, look up any vocabulary that you aren’t 100% sure about and write the meaning or translation above the word in the article. A great annotating tool is Kami.com.
Find and number all of the main points in the same margin. The reason for that is so that you will easily find all of the main points and be sure to include all of them in your Summary. By putting the numbers in different places within the article, you will easily miss some of them when you are writing your Summary. Lastly, write some good questions about the article, and then also develop your response. What thoughts/stories/ideas came to your mind while you are reading the article? You must write them down in the article – that is your preparation for your essay.