By Jamie Allen
CNN Interactive Senior Writer

(CNN) -- Now more than ever, cruises can be a vacation gamble. Not that there's anything wrong with cruises. But since the industry skyrocketed in popularity and variety about 10 years ago, few other getaways may require as much research to land the right one for you.

Clearly, if you pick the one that's not right for you -- if you're a 20-something partyer and you find yourself surrounded by ocean, senior citizens and shuffleboard -- the captain is unlikely to buy your seasick story, turn the big boat around and take you home. That's why it's vital to plan your cruise carefully.

"If you do your homework, you're going to get an 'A,'" says Jim West, author of "The Essential Little Cruise Book : Secrets from a Cruise Director for a Perfect Cruise Vacation." "If you don't do your homework, you're going to get a 'C.'"

West knows -- during his decade as a cruise director, he kept a journal of passenger complaints, the basis for his softcover book, the second edition of which is to be published in September by Globe Pequot Press. The first edition came out in 1997. West advises the cruise-bound to dive into research, for the best chance of finding a cruise that caters to their needs.

For that 20-something partyer, for example, West says Carnival cruises might be the ticket. "They cater to a younger, sometimes more rowdy crowd, though they're trying to change that image a little bit."

But, West says, the best cruises provide entertainment for everyone. "The real wonderful cruise experience is (offered by) a cruise line that can provide activities and stimulation that can mesh with all ages."

Getting started

Once you've decided that you're heading to sea, the first step in planning your vacation is to buy a few cruise books at the local bookstore, get a feel for what's offered. Then start asking questions.

Friends and family who've been on cruises may be trusted sources. Travel agents, of course, might be, too. But don't settle on just one agent right away. West first recommends asking three questions of each agent.

First question, an obvious one but important: How many cruises has the travel agent been on?

"If they've been on 10, great," says West. "If they say they haven't been on one, it's time to move on."

Second question: What kind of cruise lines do they promote? Some travel agents will push certain lines not because they're better, but because the agents get higher commissions if they sell more with one line. Look for an agent who offers a variety of lines.

Third question: What makes this travel agency better than the one down the street? If you've found a good travel agent, you'll be sailing into a sea of research.

"They should really ask the clients lots of questions," West says, regarding preferred destinations, budget concerns, activities they're seeking. And they should provide a heaping pile of brochures.

What can brochures tell you?

West says there's only so much you can learn from a ship's advertising flyer. You'll never see the lesser points of a ship that way.

But Karen Cure, editorial director with Fodor's, says brochures can reveal important characteristics of each ship's clientele -- i.e., the people with whom you'll be stuck at sea. "Look at the pictures of people in the brochure," Cure says. "They all market to a different segment."

Sure, most commercial photos use models, but if they show young models without kids, chances are the cruise caters to that demographic. If they only show couples watching a sunset, chances are the would-be Austin Powers might not find a willing mate to court.

Also, "If you see a lot of pictures of places in the brochure, then it's a pretty quiet ship," says Cure.

'You have to be flexible'

It's at this point you should decide what you want to do on the ship. Some trips offer interesting lectures. Others offer an endless schedule of party games, loud music and gambling. And still others are willing to take care of the kids while the parents sun on deck.

"If you're going to take kids, you obviously want to make sure there are other kids on the ship," Cure says.

Other things to consider: Do you have special medical needs? Do you want to sail in off-peak seasons, or do you want to leave the Y2K bug to the landlubbers and head out on a New Year cruise? Would you like a daily massage? Would you like to eat seven meals a day? Would you like to do a lot of sightseeing? Shopping?

Decide what you want to do, even decide on a general destination (the Caribbean or Alaska? the Mediterranean or Mexican Riviera?). Then start pricing. Ultimately, you should go with the travel agent who offers the best deal, but you might want to use the Internet (again, research) to find good deals, then ask an agent to better them.

And West has one more bit of advice, after you've paid for the cruise and you're ready to embark: Let go and have fun.

"The bottom line is you have to be flexible," West says. "Anything could go wrong, and it sometimes does. You have to go with the flow for this entire experience. No matter what the travel agent tells you, no one will be there to take you step-by-step."

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