Hi Fred and Keith:
I hope you enjoy your first cruise, although your prior one sounded amazing, I'm sure this will be a great time as well! You'll get your feet wet and be back for more, hopefully!
Making your dollars stretch with the Sail and Sign, Sea Pass or whatever cruise line card is not too difficult.

The first thing to avoid (on Carnival) is the beautiful drink they will thrust into your hand the moment you walk on board...or maybe after you offload your carry-ons in your stateroom, and you come down / up to the lido deck for the grand, Sail Away. The bar staff is good about putting a beautiful glass with a pretty drink in your hand. That will be $15. lol...or there abouts.
Many, if not most cruise lines tell you not to bring your own alchohol on board. The exception to this is that you're allowed two bottles of wine upon boarding. Additionally, you can bring back on to the ship another 2 bottles in every port you are in.
I am not condoning this mind you (

) but I know of many, many passengers who smuggle alchohol on board, by means of water bottles, etc. Of course this saves on your ship charges, if you enjoy a libation or two...or three.
Bring your own insulated water bottle or thermos (if your bringing booze, bring another one). The ships like to sell bottled water and will greet you as you exit the gangway, at each port. The water is astronomically high, and it's plain bottled water. My partner and I each bring our insulated Starbucks mug...we use for coffee, iced tea or whatever. It easily fits on our side pouch of the backpack and it saves $6 each at every port. Besides, we like iced tea so I just make some at breakfast before we disembark the ship. It works. Alternatively, you can visit a store while you are in a port and bring back onto the ship your own bottled water, for a fraction of the price.
Like most good gay boys, you'll love to shop. We love to shop. We've learned to do more window shopping at first - on the cruise ship. Do NOT (I repeat, "Do NOT") impulse buy. Ask the shop steward when they will have their sale. Every cruise line does, all the shops have a special sale. It's tempting to buy fun novelties, t-shirts, sarongs, etc, but wait until the sale hits. You'll likely save 40-50%.
If you like to gamble a little, stick with the quarter slots, lol. They usually don't fail me, and I just budget a little extra for this entertainment and when it's done, it's done.
Most everything should be covered in the cost of your cruise, with the exception of alchohol, Spa services and things you purchase from the gift shops.
As for getting the GLBT ball rolling, put a call into the "Cruise Director" as soon as you board the ship. See the pursor (lobby assistant) or ask your stateroom attendant who he / she is, and their number. It's gladly given out. You may want to first check the Carnival daily news, which will be laying on your dresser or bed when you board. Look at the day's activities and see if there is a "Friends of Dorothy" meeting scheduled.
HTH!