One thing I can recommend - if you can, find an itinerary where your first day is a day at sea. This will give you a day to get your bearings on ship and de-stress from the journey to your port (especially if you don't get to your embarkation port until the day you sail).

Besides, there's something magical about waking up your first day and being surrounded by all that water.

Get the best cabin you can afford, and I do think a balcony is worth the money! (A balcony cabin may also be a little larger than some of the others, and you will have 4 people in yours.)

Also, I highly recommend finding a good cruise travel agent for your first cruise, since he/she should be able to quickly advise you on what's a good choice or a bad choice. Unless you really like doing all that research and agonizing.