from Istanbul to çanakkale, you can take the bus from the terminal. from Çanakkale to Selcuk, better to take bus to İzmir First and then from İzmir to Selcuk.
from Selcuk, you can get a Direct bus to Istanbul, or to İzmir then to Istanbul. İzmir and Istanbul are the hubs.
or you can rent a car from Istanbul and make it much easier ;) over 6 years ago
If you would like to travel by plane, you can fly from Sabiha Gokcen Airport to Canakkale Airport. Also there is a new flight to Gokceada a big island close to Canakkale. But I am not sure if you can find a flight directly from Istanbul.
For flight lists you can check http://bulucak.com/ (has an English link) for all local flights.
Also you can check www.anadolujet.com and www.thy.com.tr for airlines companies that have flights.
Istanbul-Canakkale flight takes only 1 hour and the cheapest ticket (for early bookings from Anadolu JET) is 60TL (~30Euros).
If you want to take a bus, -as replied above- you can take buses from the bus terminal directly to Canakkale or Izmir. Istanbul-Canakkale takes ~6 hours by bus.
From Canakkale to Selcuk, you should arrive first to Izmir and then you can take small buses or dolmus's to Selcuk from Izmir Bus Terminal.
Izmir - Canakkale may take nearly 4-5 hours (~350km).
From Selcuk to Istanbul, you can fly from Izmir to Istanbul (first by bus/dolmus from Selcuk to Izmir). There are a plenty of flights from Izmir to Istanbul. Or you can take a bus from Izmir to Selcuk. As ersavas stated above, there seems to be direct buses from Selcuk to Istanbul.
Selcuk-Izmir dolmus's are also depart from main bus terminal in Izmir, the same terminal for intercity departures and arrivals.
These are some bus companies between Canakkale - Istanbul:
Truva Turizm and Metro Turizm also have buses between Izmir-Canakkale.
If you need more details just reply or send a message :) over 6 years ago