I grabbed a selection of brightly coloured yarns, double knitting weight, and a 5mm hook, and set to work. After a bit of experimenting I worked out that I needed 99 stitches to make a piece of crochet wide enough to cover my 50cm/20" cushion insert that I'd bought from Ikea, and I worked two forward and return passes of simple stitch for each colour, starting each new colour on the return pass. Here's a good basic guide to Tunisian crochet by Simply Crochet.
I tried to use the colours fairly randomly to give a fun, striking look to the cushion. I just kept going until the piece was long enough to fold over and fit the insert, with a bit of overlap to put buttons on. I definitely got the hang of Tunisian crochet by the end of it, and it was the perfect texture for a cushion cover - lovely and thick with no holes.
If you've never tried Tunisian crochet, I'd definitely recommend giving it a go - you could always try something much smaller, like a case for a phone or your sunglasses. My cushion is now brightening up my new craft room, and coming outside with me when I'm enjoying the sun.
