I would think if you are stuck in New Orleans area, you would want to seek shelter in a tall (probably over 3 story) steel reinforced concrete building that is sturdy and fairly modern. If it is a hotel you would want to fill up bathtubs with fresh water, and get as much as you can. Grab as much shelf stable food as you can and first aid kit at a minimum.
New Orleans I hear has about ten shelters opened for the public. One is the Superdome which is located on some of the highest ground in the city.
Regardless, don't panic, but plan as intelligently, reasonably, and quickly as you can.
Not sure if it's too late to evacuate. I think they have both directions of traffic opened up now though. If you choose to evacuate be aware of the possibility of getting caught in the open if traffic doesn't move and take that into your planning considerations.