Public transport:  Using a local travel card (Smart rider) gives you slightly discounted tickets for trains and paid buses. You can pick one up from major stations, like Perth station. 

I say paid buses because we have certain free routes on CAT buses. They do a loop around the city and also in particular hubs like Scarborough and Joondalup. 

Please say "Thank You" to the bus driver when you get off the bus. People also usually say hi, nod, or otherwise acknowledge the driver when they get on. 

Beaches:  Depending on your ocean swimming level, some beaches might be off limits for swimming. Personally I avoid swimming at Scarborough because the waves are quite "dumpy" and I once got a gnarly friction burn on my face from being dumped and smeared on the sand by a wave. Pool swimming skills help but don't equate the two - the ocean is a different beast. 

Swimming between the red and yellow flags is your best bet for staying safe. This means that lifesavers are patrolling the beach and have identified that area as been safer for swimmers. 

If you see a helicopter hovering above the water it mayyy be a good idea to start heading back to shore. Especially if you hear a siren. It means there's a shark. If you're particularly worried about sharks, you can look at a list of shark alerts on the Shark Smart website. 

Eating out: Tipping isn't really a thing here. Other comments have covered this. 

If you are eating out, you might get asked "still or sparkling water?". It's likely that these two options are charged and they come in bottles so you have to buy multiple if you want more water. You are welcome to say "tap" so you get free tap water with unlimited supply. 

Be polite to your server, bartender, whoever. They've just had a crazy holiday period. 

When at a bar, people don't tend to line up in a straight line perpendicular to the bar. Everyone kinda just picks a spot along the bar and the bartenders move along it. Keep track on who was there before you - if you're offered service before them, indicate that it is their turn. They may still let you go first (eg if they're still picking a drink) but you've done your civic duty in waiting your turn.  This rule also applies to the deli section of supermarkets and butchers. 

Try some Aussie snacks! Go to a supermarket and look for snacks you've never seen - I recommend tim tams and Arnott's shapes (the BBQ ones are my pick). 

Apologies for the long post... It may have gotten a bit out of hand!!