Alexandra, most folks get accustomed to it either with more sailing or just after a bit more time on the water.
There are things you can do to prevent seasickness: No alcohol, no booze, for 24 hours before sailing and make sure you are well rested, and hydrated, and avoid things like greasy foods. Simple stuff like that makes a big difference.
For meds, everyone responds differently. Passive wrist bands that put pressure on the ne-kwan points work well for some folks. Taking ginger (ginger capsules with standard powdered ginger in them) or ginger ale or candied ginger helps some folks enough, the ginger opens up the capilaries and increases oxygen in the blood/body, it actually is doing something.
Then there's meclizine and other OTC or shelf drugs--each works for some folks and not others. Stugeron (Cinnarazine?) is OTC in Canada and the UK, a more serious med but not available in the US. Does nothing for some folks, works great for others.
And when all else fails, there are the rx meds in the US, like Compazine and Scopalamine (Scop available in pill or patch) that work very well for most folks, with some side effects like dry mouth--read the insert and check those out before trying them.
With any real meds, your best bet is to try it out at home one evening first, so you are in a comfortable place and you can either go to sleep or seek help if you do have a bad reaction. That way there's no worry about "What's this gonna do to me?" making you nervous on the boat.