To attach the cabinets to each other, use a No. 8 2¼-inch-long trim-head screw with a fine thread suited for hardwood. This fastener's small-diameter head is unobtrusive, so you don't have to hide it under a cap or wood plug.
To attach the cabinets to each other use a 2.25 inch No. 8 trim-head screw.
cabinet screw, washer-head screw, washer-head cabinet screw, or button-head screw. Its large-diameter head bears down firmly on the cabinet's hanging rail, ensuring a solid installation. Attach the cabinets to the wall using No. 8 or No. 10 screws, approximately 3½ inches long.
Use 3.5 inch No. 8 or No. 10 button-head screws to attach kitchen cabinets to the wall studs.
To installing kitchen cabinets, utilize a long level and draw a level line around the room at the base of the upper cabinets and the top of the lower cabinets using the lowest point of the ceiling and the highest point of the floor to make the starting mark. This will ensure that the cabinets are level. Shims can be used (little pieces of wood) to make up the difference as needed.