Crazy paving should always be laid on a prepared surface. To ensure that the crazy paving is level. Place three or four pats of mortar. Each about the size of an egg. On the surface to serve as a base. This makes it easier to adjust the level of each slab. Use a mix of one part of cement to six parts of sand and tap the stones down lightly with a mallet.
Fill any gaps in the paving with a thin cement mix. To reduce mess, pour some of the mix into a strong plastic bag. Cut off one of the corners of the bag. And squeeze the cement into the gaps.