First, WELCOME to the boards. Glad to have you here.
Second, you're absolutely right. A cruise IS what you make it.
Advice?
Activities - Don't even begin to think that you have to do everything. There will be so much scheduled that you'll have to take the same cruise (at least) three times, back-to-back to do everything.
Cell phone - Once you process through the terminal, and before you board the ship, TURN IT OFF. You're on vacation. There's nothing going on back in the world that you need to keep up on that badly. If there is, then stay home and take care of it. Besides, cell phone use on the ship can easily run around $9 (or more) per minute, on top of your regular useage charges ((all calls are picked up by the nearest cell tower, and that would be the ship's tower. Then they are relayed to a satellite and beamed back to Earth. This makes your cell call a satellite call and thus the $9+ per minute additional charge. The charges won't show up on your on-board account, but will on your cell bill!)).
Internet - Similar to cell phones, in that keeping in touch is one of the last things you need to be doing. Cut the apron strings. You're on vacation! Besides, the connection speed is v....e....r....r...y s....l....o....w, and expensive (anywhere from $.50-.85 per minute, can only be bought in blocks of time, and theres no credit for unused minutes....).
Menu - Try new things. If it's something you can't pronounce, or don't have the faintest idea of what it is .... order it. If you like it, great! If you don't, then back it goes and you can try something else. Order as many of anything as you wish. 3-4 appetizers. all three soups (especially the chilled ones!). Can't decide on which entree'? Order both.
Room Service - In the evening, after the late show, stop off at a telephone and order a plact of fresh (hot from the oven) cookies and a pitcher of ice-cold milk. It'll arrive at your cabin the same time as you do. Makes a great ending to a wonderful day at sea!
Tips - Tip (at least) the recommended amount. That $10-11 per/person, per/day is split between your steward, waiter, assistant waiter, head waiter and matre 'd. Those guys and gals work very hard and their salaries are pretty poor. If you have received special service, don't hesitate to tip (in cash and in person) at the end of the cruise. Along the same line, try to get the manes of crew who have made your cruise special and send a letter to the cruise lines head office citing the person. Those little pats-on-the-back go a long way and mean a lot!