A toolbox for home improvement will differ in many ways from the toolbox that is used for working on your car. It is often a good idea to prepare two toolboxes and to keep them separate. The mechanic toolbox for car repairs is going to be more geared toward large wrenches and heavy duty tools, but the home improvement toolbox needs a bit more variety.
The home improvement toolbox does need a socket set and standard assortment of screw drivers, of course, but it is better to focus on small sizes for the myriad of household jobs that will require small screws or bolts. A must in the home improvement toolbox is the electrical tools needed for wiring jobs. A box of assorted wire nuts and a combination wire cutter and stripper is a most definite need.
Home improvement type jobs often include plumbing type jobs such as the repair of leaks or the adding of bathrooms or additional sinks. Channel lock pliers and a good size pipe wrench are needed for these types of jobs. This is one of the reasons for preparing the two separate toolboxes. Many people find themselves doing inside plumbing work with socket wrenches, and trying to repair their cars with pipe wrenches.
Most home improvement type jobs involve hardware, and the size nail or nut that you need is always going to be the one you do not have. This seems to be an unwritten rule of home improvement. A good idea is to purchase several packages of assorted screws, nuts, bolts, and nails to give you a better chance of having the right size. Nothing slows a home improvement job more than frequent trips to the hardware store to buy one half inch screw.
One important addition to any tool kit is a good flash light and always be sure to keep a few extra batteries as well. A good flashlight to include in your tool kit is the streamlight flashlight. This high quality and durable flashlight is a favorite of police officers and will hold up well under the abuse of repair work. Another good idea for the home improvement toolkit is to invest in some belts and holsters, like the Galco holster which is usually used for carrying weapons, but can be used for your flashlight or other tools. The idea is that the more that you can carry at hands reach when you are in a confined space or up on a ladder; the less you will have to crawl out or climb down to fetch a tool.