I've always loved seeing neighbours yards lit up at night when running around my local area. I decided to add some festoon party lights to our backyard. It was inexpensive and adds for a bit of fun and atmosphere.
These lights were from Temple & Webster (the lights are outdoor rated and run on 240v - no transformer). I purchased a few timber offcuts from Bunnings to extend the height of my fenceposts to give me something to anchor them to. I lopped the top of the offcuts off on the angle to prevent water from pooling and gave them a quick lick of paint to match the fence. I used steel wire, a few eye hooks and a cable tensioner and strung the guide wire to support the lights (so the electrical cable wasn't supporting the weight of the lights). Then I attached the lights to the wire using some cable zip ties. I've got the lights on a smart switch so I can run them on a schedule or say "Hey Google, turn on the fairy lights"... which the kids love to do!
All in all it was $110, which included the lights and fittings for a 20 metre run of lights.