Sydney's train and subway service is definitely the most convenient and fastest way to get around the city. The network is entirely above ground, with the exception of the city circle in the CBD, making it difficult to qualify it as either a train or an underground. In any case, today it connects the main areas of the city, even if some very popular areas are not connected by train at all (for example the entire northern beaches area). The trains usually run from 4 in the morning until around midnight and the cost of the ticket varies based on the distance and the time (during rush hours the ticket costs more). Keep in mind that on weekends some routes are often suspended to carry out work on the tracks and the trains are replaced by buses.
The city's rail network is connected to the interurban network, so it is possible to reach destinations further away from the city (such as the Blue Mountains or Wollongong) with the same trains with which you travel within the city, without necessarily having to go to another station or having to change trains.
By far the largest public transport network in Sydney and NSW is the bus network. This is certainly the cheapest means of transport, but also the one most subject to delays due to traffic or roadworks. There are hundreds of lines that connect practically every corner of the city and the state, so it will not be difficult to find a bus (or more than one) that will take you to your destination. The cost of the ticket varies depending on the distance travelled, and some routes also include a night transport service, called Night Ride.
If you are at the stop and want to get on a bus, you must signal to the driver your intention to board by extending your arm out and if you want to get off the bus you must book the stop by pressing the appropriate button, otherwise the driver will not stop.
It is usually possible to buy the ticket on board if you do not have the Opal Card (the local transit card), but some express buses during peak hours will not give you this option.
It is not possible to top up (charge) the Opal Card on board, so if you do not have enough credit on the card, the driver may ask you to get off or, if the bus is too full, the driver will not let anyone on and often will not even stop at the stops, unless someone needs to get off.
You always get on only from the front door, and you generally get off from the middle and rear ones.
The light rail is in the process of expanding. I find it very scenic and the best way to reach some of the most touristy places in Sydney, which are difficult to reach otherwise, such as the Fish Market, Chinatown and Darling Harbour.
Since Sydney is a city on water, water transport obviously cannot be missing.
Loved by tourists and locals are the ferries that connect Circular Quay to the North Shore to Darling Harbour or to the Eastern Suburbs.
Aside from the “classic ferries”, there are also private companies and you can always opt for a water taxi, operated by various private companies.
You can hail a taxi on the street, go to one of the various taxi stands around the city (usually near train stations), or request a car for a specific time. All taxis operate on meters and there are additional charges for booking by telephone, to/from the airport, at night and on public holidays.
As in the rest of the world, Uber has become extremely popular in recent years and Sydney is no different. There are certainly more Uber cars than taxis in the city now and it will certainly not be difficult for you to find a ride at any time of day or night, from any point in the city.