Sydney is best visited between September and November, and March and May. These are the off-seasons, when temperatures are mild and crowds are minimal. Airfares are also cheaper now.
September to late November is just before peak season, so expect some crowds. Overall, temperatures range from low 50s (10°C) to mid 70s (24°C). The fall season (March-May) is similar, so bring a light jacket for the cooler days. Sydney's peak season is December through February, Australia's summer. People come here to enjoy the high 70s°F (high 20s°C) temperatures. As a result, it is the most costly season to visit. Sydney is safe for single female travellers. People are kind and helpful, so you shouldn't have any problems.

When in doubt, trust your gut. Scammers should be avoided. If your hotel or lodging is more shady than you expected, leave. In case of an emergency, make copies of your personal papers, including your passport and ID.As a general guideline, don't do anything in Sydney if you wouldn't do it at home. You can also get 21 seater minibus hire.

Most instances occur because tourists are unfamiliar with Sydney's peculiar climate, so bring lots of sunscreen and remain hydrated. If you go out into the suburbs, be aware of animals. Watch wary for snakes and spiders, and get medical attention if bitten. Also, if swimming, obey the red and yellow flags. Yellow flags indicate unsafe swimming conditions; red flags imply closure. From November to May, only swim where there is a beach stinger net to avoid jellyfish stings. The most crucial safety tip I can provide is to have travel insurance. Theft, sickness, and cancellations are covered by travel insurance it covers all bases in case anything goes wrong.