Installing new kitchen cabinets can really spruce up your kitchen, and it's a project that most do-it-yourselfers can handle with relative ease. Doing it properly doesn't require much more than basic carpentry skills. It does, however, require a high degree of attention to detail. The key is to remember the basics--measure twice; make sure it's level; make sure it's square.
New kitchen cabinets aren't cheap. Protect your investment by removing drawers and doors from your cabinets so they don't get dinged up during installation. Next, mark the wall where you want to install them. For standard sized base cabinets, draw a line 34-1/2 inches above the floor. (First, check that the floor is level, especially in older houses. If not, measure up from the highest point.) For wall cabinets, mark 18 inches above the existing counter top or 19-1/2 inches above the line you made for your base cabinets (this allows an inch and a half for the counter top).
If you are installing base and wall cabinets, install the wall cabinets first so you don't have anything on the ground to obstruct you. Install a ledger board along the guide line you drew so you have something to support the cabinets while you screw them in. Mark stud locations on the ledger board and then begin by installing the corner cabinet. Use shims to make sure it is plumb against the wall and then screw your fasteners through the cabinet into the studs.
Set the next cabinet against the corner cabinet, Make sure it is level and flush with the cabinet next to it, then clamp it tightly to the installed cabinet. Pre-drill holes through the sides of the cabinets and fasten them together. Shim the second cabinet to make it plumb with the wall, if necessary, and fasten it to the studs. Continue this process until all of the cabinets are installed.
To install the base cabinets, use essentially the same steps as you used for the top, only this time follow a guide line on top. Set a corner cabinet in place and use shims as needed to raise it to the guide line, make it level, and make it plumb with the wall. When you've done this, fasten it to the wall studs.
Repeat the steps you've already performed--set the next cabinet in place, shim it so it is level with the guide line, and attach it to the studs. Clamp it to the cabinet next to it, shimming as needed to make it level and plumb to the wall, and screw the sides of the two cabinets together as you did with the wall cabinets. Repeat these steps until you are finished.