There are lots of features you could consider – speaking with your client will determine their needs.
Counters and cupboards should be lowered, or be possible to lower mechanically if multiple heights are required. Sinks, especially in the kitchen, should also have adjustable or lower height, particularly for wheelchair users.
Flooring should be non-slip, durable, non-buckling and easy to clean. Vinyl flooring and laminates are ideal for wheelchairs, and cork can be good for less mobile clients as falls are dampened.
Use of lever handles and lowered handles will also assist those in a wheelchair, from chairs to cupboards. When lowering functional items, also remember to lower light switches, and raise plug sockets.
Making sure that all elements of a room are accessible is vital. Putting smart controls in convenient places to make a central control point reduces movement required in the room, and think about where windows and radiators are positioned to ensure access is possible once furniture is added.