Assuming you are referring to what type of equipment and supplies you should keep on your service truck, here are a few tips:
First, you will need basic hand tools such as a hammer, screwdrivers, wrenches, etc. You will also need a variety of screws, nails and other fasteners. It's a good idea to keep a variety of sizes on hand.
Next, you will need a power drill and a good selection of drill bits. A cordless drill is a good option as it will allow you to move around more easily. You will also need a saw for cutting wood and other materials.
Other useful items to keep on your truck include a tape measure, level, pliers, a flashlight and a first aid kit. For safety, you should also keep a fire extinguisher on board.
Of course, you will also need to keep a stock of the materials you will be using most often. This might include things like wood, drywall, insulation, pipes, fittings, etc. It's a good idea to keep a mix of new and used materials on hand as you never know when you will need them.
By following these tips, you can be sure that you will be prepared for anything that comes your way.