To start with, it has to be Agatha Christie.
I "ate" her books when I was your age...don't get bothered that the stories are a little "old" they are amazing reads, and are actually fitting for any age.
I would start with the Miss Marple stories, to ease you into her writing (well, I am not a native speaker, so I found those easier than the ones with Hercule Poirot, you might think differently thou...), but Miss Marple was the preferred character of Christie, as she got quite tired of her own creation, of Hercule Poirot, after several years and numerous books and focused on Marple instead...fun think about that: Hercule Poirot was the only fictional character to get an obituary in the NY Times, after Christie decided to drop him ;-)
Then you can go for Karen Rose, she writes a mixture of crime thriller paired with some romance on the side...
Another capturing read is Karen Slaughter - her name tells you all ;-) its really difficult to put those ones down once you started...the stories include quite brutal murders, but the comforting part about her books that the "heroes" are always some somehow screwed up characters who are not the Knights in shining armor, but each have their own package to carry. Makes them more realistic, and you feel much more satisfied when they actually "win". I like those, because the realistic main characters make the killing psychopath even more creepy.
Agatha Christie starter: 4.50 from Paddington (it is, I would say, the most popular Marple-story, so in case you are not becoming a fan of her - which I actually doubt - you will at least have read this one)
Karen Rose starter: Don't tell (this is the first one, and since the characters are kind of coming up again I would start in the beginning)
Karen Slaughter starter: Blind Sighted (the first book of the Grant County series, also you can read each book by itself, i recommend to stay in order to fully understand the development of the MCs - I myself started with the second one "Kisscut" and it was still perfectly well to understand...)
Apart from that Mary Higgins Clark is always about offering some enjoyable hours of a suspense thriller (I like her books, but I must admit I don't find them as memorable as the other 3 on top). The same goes for Joy Fielding with the exception that Fieldings "See Jane run" really got me into suspense thrillers when I was around 14 as well. Before I just stuck to Christie...
So go for the upper 3, but if you feel you need more Clark and Fielding offer you a wide selection of good books, and I would never say 'no' to one of them ;-)