Horse Not Ridden In Year :/

I just purchased a 15 year old mare the other day. The owner (and my cousin who has ridden her) says she is a wonderful, gentle horse. The problem is that she hasn't been ridden in a little over a year. I'm not an experienced rider so I don't exactly know how to handle the situation. How should I approach this? I want to ride her but I don't want to get hurt.

If she is well broke and 15 years old, I wouldn't think you'd have a problem. It's not going to be like colt breaking; there likely won't be any major drama. She might just be a little rusty. You could lounge her before riding if it would make you feel a little better and help get some edge off. Maybe your cousin should sit on her first, ride her a little bit (ten minutes or so, to make sure), and hand her over to you?

Depends on what she has done in that year.

If she has not been handled start with that, spend time with her, grooming and working on leading again.

If she has been handled start with lunging or round pen work, but don't over do it, she will be unfit.

She will not have forgotten anything, she just needs help remembering what is expected of her.

What exactly is lunging?

Lunging is when you work the horse on a circle around you either free (without any attachments) or with a long line connected to the horses bridle or halter. How much experience do you have exactly, lunging is a very common practice. I always work a horse on the ground before I get on when it has had time off. You sound nervous and fairly inexperienced so I would suggest getting someone knowledgeable to help you work her on the ground to gain confidence, respect and trust then go from there.