CruiseStar
Start with the category, not the price tag
Most ships offer four broad tiers: interior (no window), oceanview (a window or porthole, no outdoor access), balcony (your own outdoor space), and suite (more square footage plus perks like priority boarding). Pricing climbs roughly in that order, and an interior cabin is usually the single biggest fare-saving move you can make, sometimes cutting the per-person cost by 30% or more, which is a perfectly reasonable trade if you're planning to spend most of your time in the ship's public spaces anyway.
Location matters more than the category
This is the part first-timers tend to skip, and it's the one that causes the most regret. Cabins directly under the pool deck, below a nightclub, near an elevator bank, or beside a crew door are the most common sources of noise complaints, and a few minutes with the deck plan before booking avoids most of it. If motion sensitivity is a concern, aim for a cabin that's both midship and on a lower deck; that's closest to the ship's center of gravity, while cabins at the very front or back of high decks feel every bit of a rocky sea day.
Is a balcony worth the extra money?
It depends entirely on where you're sailing. On a scenic route like Alaska or Norway, a private balcony earns its keep because you'll actually use it to watch the scenery go by. On a Caribbean itinerary that's mostly port days and pool time, it's a nice-to-have rather than a must, and that money might go further toward a better excursion or a specialty dinner instead.
Size expectations, and a few extras worth knowing
Interior and oceanview cabins typically run 150-185 square feet, standard balconies 180-220 including the outdoor space, and suites anywhere from 300 up to well over 1,000 square feet on the largest ships, all noticeably smaller than a typical hotel room, so pack accordingly. Families or groups needing more room often look at connecting cabins, which need to be specifically requested since they're limited inventory. And if you booked a cheaper "guarantee" rate, you generally can't pick your exact cabin, but you can often request a general area, like asking to avoid anything under the pool deck, through your travel advisor or the cruise line directly.