At Tustin all trains going North and East are on the opposite from the parking and Bus area. Just go under the tracks using the tunnel. Southbound trains are on the closer side up the stairs. Tickets can be purchased from the machine or on the web app on a smart phone.
They have, I think, a ticket station that looks like a vending machine & takes dollars, change, & cards. It will give you a ticket for A DAY, from whatever station you want TO whatever station that is your destination. The ticket thing, will not decide the station you are at as the starting point. Also, I don't think it even gives a ticket for routes like, the pink or blue route. Regarding, knowing what track to be on is usually signs & it is different at every stations. You have to know what your first train is & know the direction. The signs are usually there & the usual riders also should know. A lot of stations only have two directions, but if you are on the wrong side usually the train will not be there when you get to the other side.
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