Just approach it just like a fretted bass, so don't try and make it sound like a fretless and do lots of slides and trying to get that mwah sound. It is no different to play than a fretted bass, you just have to be more disciplined with your technique and train your ears. Good ears and strong technique are the two key things you need to play a fretless well. Don't be scared of it either or think of it as different, just play what you'd play on a fretted and you'll be amazed at how normal sounding it can be. Over time, you'll then start to bring out the nuances of the fretless as you become more competent. The Jack Cassidy is also an unlined fretless so you either play ON the dots or in the gaps, it's that easy. Oh and buy an octave and chorus pedal, you'll thank me later I promise 😂