What to think of when booking a cabin on a cruise

Thanks Nicca for your question re motion sickness and picking a cabin to avoid the most of the movement. 
If you get motion sickness:
 Tip 1: Book a cabin on a lower deck in the middle of the ship as this is where you will have the least movement.  The higher the floor often the more feel of movement/wind.
Tip 2:  Get out on your balcony (if you book one) or get out on deck as much as possible as the fresh air helps with any sickness.  Also get your medication, ear patches or the sea sickness bands at home as its much cheaper than asking the doctor on board.
Overall tips on booking any cabin on a ship:
Tip 1:  To save money usually an inside cabin is the cheapest option or an inside "guaranteed" is usually a bit cheaper still. However the cruise line picks your cabin and I have found that often I will get the front or back of the ship.  Note however look at your cabin options as on the Oasis the Central Park Balcony was cheaper than the inside for a solo. I have also found that sometimes the guaranteed ocean view is cheaper than picking your own inside cabin.
Tip 2: If you are ok with a bit of ship movement I prefer the front of ship on a higher floor. This usually results in a bit of ship movement feel, but you don't hear the anchor dropping/being pulled up. The back of ship (on many but not all ships, has a back and forth swaying movement and you get the vibration of the engines). 
Tip 3:  Look what is above and below your cabin - avoid having the sun deck, casino and or restaurants or pubs below are above. The best is to have cabins below and above you to minimize noise.
Tip 4:  Do not book a cabin with adjoining cabins if they are not your friends or relatives as you can hear noise, tv etc thru the adjoining cabin door.
Tip 5:  Unless you have 3 or more in your cabin don't take a cabin meant for families as even though I am not tall its awkward to move around the cabin with the bunks on either wall.  You lose the side space for getting in and out of bed without hitting the bunk(s). I have been assigned these types of cabins thru a guaranteed cabin purchase.
Tip 6: Given you will have limited space - usually your empty luggage fits under the bed.
Tip 7:  What if the guaranteed cabin they give me is not what I want?  Ask your travel agent to call them - I have upgraded/changed my cabin for either a small amount or free.
Tip 8:  Cruise lines are all different on the timing for assigning guaranteed cabins.  NCL if they are sellling out on cabins often assign the cabin about 90 days before the trip but not always.  On Holland and Princess it can be just a few days before sailing.
Hope this helps