For a hot day on the beach, take some shoes, because when it is hot, the sand can really hurt, oh yes. Cover your feet properly, some beaches maybe a 200 meter plus walk, OUCH! Little tents are becoming more popular, specifically designed for the beach. Besides a tent or a towel don't bring that what you can't take into the water (you may need a pouch), that includes the car park.
For your safety, Australia's main beaches are patroled by lifesavers, and "flags" are used to designate safe swimming areas for the public. A
"rip" or "current", is a strong current of water that travels away from the shore
very quickly & can run for up to more than a kilometer away! A rip is caused by gutters underneath the water's surface which can channel the water. Always choose a beach with flags, not a beach without flags. If there are no flags or lifesavers, & you have to go in, be careful, get advice from more than one local you trust (eg. local dangers like Jelly Fish, etc)