I would recommend using at least one other cross-reference Bible in your pre-study. You will be discouraged from using anything other than the New World Translation with the witness since they consider it the most accurate Bible ever. Remember though that until 1950 to 1960, they only used other Bibles only have parts of the NWT in English to prove and support their doctrines and teachings.
Remember to read the scripture in context. The Watchtower Society is notorious for using snippets (phrases) and cited scriptures and flooding the paragraph with so many that only an intrepid Bible student will find the time to check them all and read them in context.
Don't be afraid to ask questions and if you are told that the question is answered later in the WT book, ask to be shown at least where you can read it later at your convenience. Don't be surprised if they can't find the passage.
Here is a site that has many Bibles and puts the passages next to each other for easier comparison. Sorry, it doesn't pull in the NWT.
http://www.biblegateway.com/