There is good caravan parks along the Murray in towns near Mildura, possibly in Mildura too.
A lot of them have en-suite cabins which aren’t that expensive at some. If you belong to RACV or similar in another state some of them have lists. At caravan parks / holiday parks there is often the option of a powered site or site with no power. There is a few parks along the coast., on Morning Peninsula and the Grampians that are popular.

We loved –
Cumberland River Caravan Park, just along from Lorne.
Buchan is beautiful.
Bright and surrounds – although it gets crazy busy in summer.
Enjoy your adventure

If you have an RACV membership, you may get discounted rates at certain parks. We do with RAC in WA, too.

Depends where you’re located. I grew up around Geelong and had my first camping experience at Anglesea. It was close to the beach and close to things to go off and do through the day. Otherwise, friends of ours have camped up around Echuca along the Murray River. Again, it’s close to things to do through the day. The kids went swimming in the river.

What part of Vic are you looking at? We love Wilson’s prom and the Grampions for good caravan parks but opposite ends of Vic haha

We get cheaper sites through membership of some parks.

Maybe for first time campers start off with parks for vans and tents.
They can be searched for online and compared and rated for your needs.

Wilsons Prom is just stunning, great camping. There are also great camping areas around Ballarat.

We always loved Wilson’s Prom and Kilcunda when we lived in Victoria. Wilsons Prom is very family friendly, Kilcunda is a little ‘wilder’.