Hi Wendalls don't be scared about doing a more intricate cake shape. I have done petal shaped. I used the petal shaped tin and covered with fondant as usual but I bought a curved edge smoother. It helps to get inbetween the curves. it comes in handy for heart shaped etc too. Make sure you measure the depth and width so you roll out enough fondant to cover it so you're not pulling on the fondant and tearing.

I always smooth across the top first so and then use my hands to smooth upwards and ease the pleats out that form. Smooth into the indentations and the fondant naturally falls into the curves. It's quite an easy shape to cover actually. Give it a go it's a lovely shaped cake. Good luck