Your professor may use a lot of long and hard vocabularies. Do not attempt to write down every word the professor says. Instead, focus on the main ideas of the lecture. Write down key topics, words and phrases. Include examples for each topic. Write down any questions the professor asks to the class and possible answers. If the professor refers his lecture to any specific pages in the textbook, write the page number down and go back to it after class. Highlight all key concepts the professor mentions.
ESL students are often intimidated and shy about their language proficiency. Do not be afraid. When you can't understand a certain part of the lecture, ask questions in class. This not only slows down the lecture, it will also clear up your questions. If you find it impossible to interrupt the professor's lecture, put a question mark on your notes and ask the professor after class to fill in the gaps.
Look up vocabularies of the text before class. Write down the meaning in both English and your native language. This will enable you to understand a lecture easier. Depending on the course content and your language proficiency, consider bringing a dictionary or an electronic one to class. When you hear a phrase that sounds important but if you do not know how to spell it, jot it down phonically or ask the professor to spell it out. Try to look the word up with your dictionary in class so that you can refocus on the lecture immediately.
Avoid sitting next to another ESL student. Make friends with native speakers and compare the notes with them during or after class. If you miss a significant portion of the notes, ask them if they would let you borrow their notes overnight or make photocopies of them. Ask them to help you if you have questions regarding the lecture.