Now is the time to assess your feelings and see if you are truly ready for such an experience. How many times have you dived after you got your certification? If you're a beginner, then try to stay above sixty feet or so. If it isn't, then how deep have you gone on your previous dives? If you want to go for deeper dives, make sure to do it gradually.
Although it goes without saying that your diving gear needs to be in optimal condition, the gear should never be new. This isn't the time to try your gear for the first time and find out that the mask you are wearing fogs underwater, or where your inflate button is on your new gear. You need to be confident with your gear before you set out.
Asses the diving conditions. The depth of the dive isn't the only thing worth considering. For example, a one hundred and ten feet dive in the calm warm clear waters of the Caribbean can never be equal to a seventy feet dive in the cold currents of another place.