One of the things that stands out in the renter's guide is the use of a cover letter to go along with your application for an apartment. A cover letter allows you to "frame" the conversation about your poor credit. For example, if your bad credit was due to a prolonged illness that kept you from working, but you have recovered and are making good on all of your past debts, that takes you out of the category of being a 'deadbeat' and a bad risk. Or if your poor credit was due to being laid off when the economy collapsed, but you are working now and have made payment arrangements to make good on your debts, you are a responsible person who went through a bad period. That is different than bad credit because you just can't get it together to pay your bills in a timely fashion.
Take a look at that renting guide. You'll get some good hints from it on how to handle your situation. Good luck with your apartment search.
Look into a guarantor or a lease guaranty company. Sidenote: Please dont expect broker jesus to swoop down with a magical apartment that accepts bad credit in Manhattan. The landlords are very strict and inventory is very low. If you cant find a guarantor or get a lease guaranty company to help you, find a private owner who will help you out or save your money until you can afford a very large security deposit or a full years rent up front.
The advise you've been given is all good; either search for a Guarantor, look into Insurent (insurent.com) or consider having 1-years rent prepaid in Cash upfront. Not knowing what your credit score is and/or the reasons for bad credit also limit the options and explanations we can provide to you as an Agent. Certain property managers view certain credit issues in a different light than others.
A guarantor is your best bet. After that you would be looking at either advance payments, additional security or both. And not all landlords will do those. And you will still need to prove annual income equal to 40 Times the monthly rent.
Depends on just how poor the credit is; also much will depend on the landlord/building, each is different; however you can consider being upfront regarding your credit; be prepared to show proof of employment/pay stubs; possibly pre-pay some of the rent; possibly offer extra security; have some reference letters handy; consider a guarantor, etc.