From the airport, take a train to Zürich central train station (HB).
At HB take the S4 train on platform 21 (underground).
Train is running every 10 min at rush hours and every 20 min during the day (HH:18, HH:38, HH:58)
Stop at the 4th stop, Brunau (6 min after HB)
Go up the stairs, go down the hill up to the 2nd street coming on your left. Cross the street, its 20 m on your left. Ring at S. Andrieux. Then 3rd floor.
If you need a SIM card (most of the time Lebara), you'll find them at some Kiosk points (where you can find cigarets) or at Interdiscount at HB central station.
Please load the app SBB/CFF/FFS Mobile to get the time table of all public transports in Switzerland. It is a really convenient app.
Public transport tickets. Please check also on your own because prices and option may have been changed. The agent of SBB/CFF/FFS (federal public transport) are always pleased to help.
One course is always minimum CHF 4.5
24h city ticket, city center including airport: CHF 8.80
ZüriCARD 24h big Zürich, with airport, Uetliberg mountain, boats, free entrance to mainy museums: CHF 24
ZüriCARD 72h big Zürich, with airport, Uetliberg mountain, boats, free entrance to mainy museums: CHF 48
Switzerland:
They offer a fantastic 22000km pass on all buses, trams, urban trains, national trains, most of the mountain trains (Jungfrau Joch is excluded for example but you receive a discount), boats, .... around Switzerland. The public transport here is really convenient and getting this ticket if you are planning to travel around Switzerland is the best option