Have confidence in your decision...make a little change for your client and stick to it. If it doesn't work for them, they will move it back but 9 times out of 10 they will keep it there and realize that it makes more sense.
How do you make a change?
Get to know your clients needs and patterns. The more you are aware of these things the easier it is to see the small changes needed. Most of the time it is a matter of common sense. When a person moves into a house things get put where ever there is room and it might make sense. But as you live in your house things change, you become more comfortable and things don't move to the most practical place. This is when a fresh pair of eyes helps to see the obvious.
Things to consider...
*How tall the clients are.
*Clients ages (older clients may need things more in reach)
*Do the clients have children that need to get at items or may need to be kept out of items.
*Space or storage issues.
For example....I have a client...She must be 6ft tall and I am only 5'4. All of her plastic storage bowls were in the under cabinets but she uses them more than anything else in the kitchen. After discussing a plan, we decided to move some of the unused dishes down, we moved all the plastic storage containers to the upper cabinets. We also threw away all the mismatched items and kept it simple...3 sizes of bowls, only one brand of container so that all the lids in that size will fit that size bowl.