On most ships you have to pay for the other person that is not going - 1 for the price of 2. But think some ships may give a % off that. I know for a fact that Carnival's Triumph and Costa's Fortuna and Magica have 'single' cabins. I've seen both, those were on deck 9. They have one twin bed and a pull down bunk. Believe it or not some of those were hadicapped with only one real bed!
Most ships also have a single's get together at the begining of the cruise. Someone once told me Carnival has singles sitting together in the dining room for dinner. You will meet other people but not all singles.
The cost is for a cabin for a single. You decide how much you want to spend for drinks, tours, etc. But watch out - you're gonna get hooked on cruising!

Yes, sadly singles usually pay a 100% supplement to cruise alone, but with cruise prices down as they are, I think you may be able find something for a very reasonable price in Europe, even though you'll be paying almost double. And some lines may waive some or all of the supplement. Speak to a travel agent who specializes in cruises (not an online agent, a real person who specializes). A good agent will be able to help you find the right cruise for your personality and interests. Cruises in Europe do tend to be longer and more expensive. If you do look at European-based lines like Costa, you might find a good deal if you don't mind being on a ship that's not American-centric. I would certainly recommend going on a ship with more traditional dinner seatings so you'll be able to sit at an assigned table with a group of people. A la carte dining isn't really conducive to meeting others (unless that's what you want).

The cheaper the cabin, the less "supplement" you have to pay. For a porthole instead of a large window on a lower level I paid 50% (1/2 of the cabin price plus 1/4 supplement). If a window cabin it would be 75%. For a balcony cabin, yes, you would have to pay for two.

It's like a sliding scale When only one person in the cabin, you pay tips only for yourself, not for two.

You have a choice: either find somebody to share the cost, or check on-line if travel by yourself is affordable. These days when economy is not so good you should be able to find a cheaper cruise.

If you are not getting sea sick and don't care where you cabin is, you can get a cheaper "guaranteed" cabin, they will let you know the cabin number closer to the sailing date.

Some cruise companies are cheaper then other. Do a comparison shopping. I like Expedia to look up prices, itineraries, plans and availability.

With Holland America you can sign up as a single and take your chance on them finding someone to share the cabin with you. In most instances they don't have anyone else and you get the cabin to yourself for the price of a single. It is a chance you have to take though.

Thank you one and all for your comments, i'm new on here & this is excellent. Hopefuly i'll get a result & be able to pass on some titbits.

Many Thanks.

Just back from a caribbean cruise on Royal Caribbean and it was great! I'm 46 and single gal, but was fortunate to find 2 others to travel with for this cruise. Thinking about doing a Mediterrean cruise next year, and might be doing it alone if can't find travel mates. But I noticed on this RCCL cruise, they did offer a "singles" meet type thing each night. We had a few single people on our shore excursions, and they seemed to feel perfectly comfortable traveling alone. I don't know if I would want to share a cabin with a stranger (pretty tight quarters!!). A cabin all to yourself is pretty nice! The biggest problem when traveling alone, is the cost, but if you are not picky about cabins, I'm sure you can find something nice in your price range.

You could check out here - they offer single options. http://vacationstogo.com/singles_cruises.cfm
(I've used vacaytogo for cruises and never had a problem.)