Hi and "welcome aboard",
a good starting point is to let us know what you expect from a cruise vacation, what is important to you (e.g. gourmet food, high-class entertainment, sports activities etc.). Also, what is not important. Do you enjoy dressing up or would you rather prefer a more casual cruise? What destinations are you interested in? Would you prefer a cruise on a large ship with up to 3,000 (or more) fellow passengers, offering an abundance of choices, but certainly not an intimate experience? Or rather a small ship? A "mainstream" cruise or rather a niche market (e.g. destination-focused or soft-adventure) or even a premium- or luxury-style cruise?
As you can see, there are lots of questions you have to ask yourself in order to get the maximum out of your cruise.