Hi Hoboken Apartment, I would strongly recommend that you hire a professional to help you with this, and actually, sorry for the bad news but I believe the deadline has passed so you may have to wait until next year to appeal. You may be hurting yourself by using comparable sales in newer buildings for example who's taxes are based off of higher assessment values..
You can contact Stack and Stack - he is an expert at appeals, I hired him to do my own and he saved me over $2000 annually. His fee is just a flat $500 and he will do all of this work for you.
Stack & Stack 90 Hudson Street Hoboken, NJ 07030. Phone: (201) 659-1000. Fax: (201) 659-0674.
Best of luck!