I did a 3 week tour of Turkey last September...it is a stunning country, amazingly beautiful (especially Cappadochia, which is unique and unlike any where on earth!) and wonderful people. Here are some quick basic links for you...
Book your hostel in Istanbul before arrival (I recommed the Sultan or Orient Youth Hostel from Istanbul Hostels - dorms from around €7 per night!) and they will probably collect you from the airport in their free shuttle bus!
The hostel will help you book onward bus travel to Gallipoli or Ephasus, Parmukale etc! Plus on the same street as these hostels that are right in the middle of the old historic center of the city you will find at least 4 or 5 travel agents that will book you onward travel in cheap and comfortable point to point coaches - or try the Fez Bus backpackers touring co.
like these for example:
Istanbul (obviously !)
Gallipoli - stay at TJ's Hostel in Eceabat! Web siteTel: 90 286 814 3121info@anzacgallipolitours.com - And ask for the tour of the battlefield by Kenan (pronounced Canon, yes Canon, like the camera !) - he is a world renowned historian and expert on the Gallipoli Campaign!
Ephasus / Selcuk
Pamukkale, Troy and Hierapolis ruins
Saklikent Gorge - a fantastic natural wonder (a moutain split in 2 by an earth quake !)
Fethiye (can pick up good boat / gulet cruises here!) and Oludenez beach (where they filmed the Blue Lagoon movie, and the best place in the world for Paragliding !!)
Olympos (that's where the famous Treehouses are!)
Lake Egirdir
Cappadochia & Goreme (this is the place for a balloon flight, but they're not cheap!)
Mt Nemrut and that region
just a few ideas to get you started. Also, use the links in my post above like Fez Bus - they have some very good options ...
I hope this is helpful,
have you got your LP or Rough Guide or Lets Go guidebook yet?