If you want to create a random shape, then the shapebuilder tool might be the best way to go about it.
You can merge 2 shapes together, cut out bits and trim stuff.
Holding down ALT & dragging across a shape with the shapebuilder tool will delete that object.
Remember to select the shapes that you are editing, with the selection tool, before using the shapebuilder tool
Stupid Mistake I made doing the flower – I didn’t overlap the circles, so the shape builder tool wouldn’t merge them.
The intersection of 2 circles make great leaves
You can also use thin rectangles to make lines: