With a complex kitchen before starting the installation I draw the entire kitchen on the walls with heights and widths. By drawing the plan on the wall all the possible problems become apparent first thing, and so can be dealt with quicker.  Pin up your cabinet installation design plan on the wall and start with finding the top level line of the base cabinets, which will be 34.5” up from the highest point of the kitchen.

Start by using a large level, or a horizontal laser level to determine the highest part of the kitchen. At the highest point put a mark on the wall at 34-1/2" from where the finish floor will be, and not from the sub floor. Always bring the cabinets up to what the finish floor will be to make sure the appliances fit well.

Next set up your rotary laser, or use a 6-8 foot level to mark a level line all the way around your kitchen. I really like the rotary laser as a tool because your guaranteed perfectly level cabinets all the way around even in a very large kitchen. The cabinets must be shimmed up perfectly level and not follow a slope in the floor. If the cabinets are not level the appliances will sit out of level, your back splash will look crooked, and round things will roll off your counter!

By drawing the cabinets on the wall the interplay of heights between refrigerator panels, tall cabinets, and wall cabinets becomes crystal clear. The widths, and exact appliance locations becomes apparent along the best place to put any fillers. The critical height of the crown molding if going all the way to the ceiling and if a crown nail-er is needed is discovered at this stage.

As part of the plan drawing mark where all the studs are located. Find the studs with a stud finder and the test the location by hammering in a finish nail. Think about your under cabinet lighting at this stage, and check if the wires coming out of the wall just under the bottom shelf of the cabinet. 

By putting your cabinet plan on the wall you become very prepared to start confidently installing cabinets in the correct positions. Kitchens are very detailed, and there always seems to be a problem, and catching it at this early stage can help.

Usually I start with hanging the upper cabinets so I’m not tripping over, and beating up the base cabinets. If a crown nail-er is needed be sure to attach it before the cabinet goes up.

First install the corner cabinets. Use a cabinet stand or ledger to hold the cabinet up while attaching the cabinet. Measure and drill holes where the studs are located top and bottom of the cabinet and start cabinet installation screws in the holes. If there is under cabinet lighting then drill a hole for the wire under the cabinet just under the bottom shelf. Try to get at least 4 screws in every cabinet if possible.

Put the cabinet on the wall on your stand, or ledger and start one screw to hold the cabinet in place. Next use your 2 foot level and some shims to level and plumb the cabinet. Fully attach the cabinet to the wall using a cordless screw gun, or impact driver. It is very important to get the corner cabinet perfect because the rest of the cabinets connect from that point.

Next hang the wall cabinets that need to be in an exact spot. An example of this would be the wall cabinets on either side of the hood, or a certain distance from a window. You know these locations because the plan is drawn on the wall.

After this install the rest of the wall cabinets. When two cabinets are together clamp the frames together, pre drill and put in three 2-1/4" finish screws to hold the frames together. If you have fream-less cabinets then use sex bolts between the cabinets to hold them together. 

Attach fillers between the cabinets that don't meet again using clamps and 2-1/4" finish screws. Rip the fillers on a table saw to fit nice and tight. Fillers that end up against the wall must be shaped to fit the wall if it is out of plumb, or not flat. I use a scribe to mark the filler and then use a bench top sander, or hand planner to shape it. 

Set the tall cabinets and refrigerator panels in place, but don't attach them. The base cabinets and the wall cabinets have to meet a tall cabinet together, and if they don't then you will have to adjust something, or put in a filler. 

Start putting in the base cabinets the same way as the upper or wall cabinets. Install the corners first, then the critical placement cabinets, and then fill in the rest. Always shim the base cabinets up to the line drawn on the wall. If you have to shim the cabinet up more than the thickness of a shim then use strips of plywood or wood that run from the wall to the front of the toe kick under the cabinet, and screw it to the floor. Keep every thing nice and level as you go.

Remember that in your layout stage you thought about the height of the finish floor and brought up your layout line to accommodate. Always install base cabinets to finish floor height so your appliances fit correctly.

The base cabinet must sit by itself level before attaching it to the wall. Before attaching the cabinets to the wall use a string line or a long level along the front of the cabinets to keep them in a strait line. Use shims between the cabinets and the wall to keep to front of the cabinets in a strait line, because all walls are wavy!

Attach the cabinets to the wall using cabinet screws in as many studs as possible. Attach the cabinets together the same way as the wall cabinets, with 2-1/4" finish screws for framed cabinets, and use sex bolts for frame less cabinets.

When cutting for plumbing or electrical always make as small as hole possible. For round pipes use a little bit bigger hole saw, or a spade bit for smaller holes. For cutting square holes I use an oscillating tool saw if the plywood is thin, and a circular saw or jig saw if the plywood is thick.

As far as attaching trims like crown molding or light rail I use a pin nail gun and glue. Cabinet nails should be as invisible as possible. Most cabinet companies have touch up kits available with matching wax hole putty.