Statistically, most of your customers are right handed. They have a tendency to focus and lean towards that side, too. Place high margin products to the right so that they are easier for your customers to reach.
Supermarkets are a great example. You'll find more expensive products to the right when walking down the aisle. Check it out!
The same is true for height. Place high margin products at a convenient height. Low margin products, on the other hand, can be placed either very high or low in your shelf.
Be aware: In some countries, where people drive on the left side of the road, you might see a difference how shoppers navigate in your store.