This is a really good question! There's a great range of Star Wars "Expanded Universe" novels out there - but it can be a little daunting deciding where to start!
You might already be aware of this - but after Disney took over the Star Wars franchise they announced that all of the old Expanded Universe novels and comics would no longer be considered "canon" (i.e., they wouldn't be acknowledged as having officially happened in the Star Wars universe).
If you don't mind reading non-canon novels, I'd recommend starting with Timothy Zahn's Heir to the Empire
. It was the first Star Wars novel set after Return of the Jedi
, and really kicked off the whole Expanded Universe. I first read it around your age, and it got me immediately hooked on Star Wars books. If you enjoy it, there are two sequels: Dark Force Rising
, and The Last Command
. Chances are you won't find these books at Whitcoulls or The Warehouse, but you should be able to find them in most secondhand bookstores. You can also buy them for around $15 each through the Mighty Ape links above.
If you want to read a canon novel, there are three that have been released so far: A New Dawn
, and Heir to the Jedi
. Because they're new, you're more likely to find these in shops like Whitcoulls - but they're only available in hardback at the moment, so they'll cost you a little more. I'm currently working my way through Tarkin
and finding it a pretty fun read!
Do you have any favourite characters, eras, or types of stories? I might be able to make some more recommendations based on those