I don't recommend using peat moss. It's expensive and adds nothing in the way of nutrients to the soil. A nice organic compost will make the soil light. Cheryl

Likewise for the sand, it doesn't help drainage until you add a very significant amount. You get the same drainage benefit from adding organic matter and it also adds nutrients.

Clay only becomes problematic when it gets too wet or too dry, its the best soil to have when the moisture is right. So add lots of organic matter in the form of mulches, compost, shredded leaves, etc, to moderate the water level.

Kyle