I'm not finding a lot of detail on use of the subway, Tunel, trams and buses in Istanbul. I did find one online subway map.
First question: where are tickets or passes purchased? Is it one standard fare per trip, are there zones, etc? Any other tips?
thanks

The street cars and subway are single tickets purchasable at a booth. Istanbul has the curious system that even the street-level streetcar stops have barriers and one must go through a turnstile to be on the actual platform. But there is a booth outside that area where a ticket can be purchased. While there is a transfer point between the streetcar and the subway station at Taksim Square (using the funicular), each mode is paid separately, including the underground funicular. My impression is that in all cases, including buses, there are no zones. Others may have more information.

They accept cash on every bus - bus fare is 1.4 or 1.5 YTL. The bus fare for a bus from European side to Asian side will cost twice more.

Tokens for tram and subway can be purchased at kiosks that are located near turnstiles. A token costs 1.4 YTL.

You pay at the entrance and you can go to the last stop. Tourists don't actually need a pass, you won't save any money.

Here's an informative page on Istanbul transport:
http://www.turkeytravelplanner.com/g...ort/index.html

That turkeytravelplanner website is indeed outstanding and I'd overlooked the great transportation information.
Thanks for all the replies.

The tram uses tokens and you can buy them at any kiosk. Be sure to ask for metro tokens when using the tram. You'll find the tram easy to use and very convenient.

PS The metro is a cheap and easy way to get to your hotel from the airport. If you need more details I will be happy to help.

"Be sure to ask for metro tokens when using the tram."
Sorry P_M, I'm not getting that, are both tokens the same thing?
Or at the kiosk, I ask for one or the other?

By the way, I read your trip report, very helpful.
I'll be staying on Taksim Square, so I think the tram will come in handy. I tend to be bus and tram-a-phobic in new cities. For subways/metros, I easily figure out the routes and the maps and the procedure--insert ticket or token, pass through turnstile. Buses and maps intimidate me more as there are more municipal variations,it seems to me--pay when you get on vs pay when you get off, how to tell when it's your stop, how to signal you want to get off, where do you wait to go on the return route, etc. And I've bought a basic phrase book, but essentially speak zero Turkish. And, I'll be a solo traveler, and I'm not the world's best navigator.

Sorry if that was unclear, the tram is called the metro. The reason I brought this up is because I overheard a lady at the kiosk asking for bus tokens when she meant to say metro tokens. I don't know about buses in Istanbul as I only used the metro (tram). The tram is very similar to what you described, just put the token in the slot and walk thru.