You will wake up in a church. Meet and name Aeris after talking to her for a while. Reno (a Turk, a group employed by Shinra) and some guards turn up. Go out the back door, to the right, jump over to the stairs, go up them, to the left and jump over the gap. Aeris will fall while trying to escape. She will be chased by three guards, you can choose to make her fight them (a bad idea as Aeris is pretty weak), tell her to wait or run. The best way to do it is to tell her to wait, then get Cloud to push the barrels off the roof rafters to take out the guards. The correct order in which to push the barrels is left-most at the back, right-most at the back and right-most at the front. If you push the wrong one, Aeris will have to fight the guard herself.
After Aeris has got away, she will come up to where Cloud is. On the next screen, go up the rafter that leads out to the roof, (the second one) and Cloud and Aeris will talk for a bit. Jump across the roof tops and get back to ground level. Go to the northwest, there is a Save Point here, then keep going northwest then north to reach the slums. Go see the guy in the pipe, and you can also buy materia, armour and items here. If you are feeling particularly mean, you can nick 5 Gil off a sick kid in the top floor of the building on the right by looking at the drawer and picking the third option then the first option.
Go to the far right to get to Aeris’s house. In the lower level of the garden is an Ether and Cover materia. Go into Aeris’s house, meet Elmyra, Aeris’s mother, answer however you like when Aeris asks you a question, then stay the night. See a flashback in the night and when you wake up, check between the bed and desk for a Potion and a Phoenix Down. You need to get downstairs, but you have to walk not run, and not touch the walls, if you do Aeris will catch you and make you go back to bed. (you can run when downstairs). Go outside, and keep going to the left, and you’ll meet Aeris again. In the next screen, go up the brown wooden walkway, along the metal hole filled bridge, down the red beam, through the tunnel, round to the left, up the wooden pole and down the brown walkway again. Go up into the playground, where Cloud and Aeris will talk again and then when Tifa rides past, follow Aeris into the next screen. Go right and up to enter Wall Market.