Pick a basic office chair with 5 wheels. You can use an office chair as a dolly by sitting on the chair and shooting with the camera handheld or on a tripod (with another guy working as dolly operator by pushing the chair in the right direction). A wheelchair is an even better option. However, this technique won't work if you want to shoot at low angles. In this case, you can improvise a homemade dolly using an old chair with 5 wheels, a skateboard and a basic plywood platform.
Remove the back rest and the seat of the chair. It should look like a pole with wheels equally spread around it.
Check the height you prefer with the camera attached. Adjust the height if possible (you can adjust the height of most office chairs somewhere on the leg area). Secure the adjustable part just enough with gaffer's tape to make sure it doesn’t move while shooting. Putting too much would make it harder for you to adjust the height of your homemade dolly for your next shot.
Cut a piece of Styrofoam a littler larger than the bottom of the camera. Put it on top of the chair in place of the seat. Secure it well with a piece of gaffer's tape. (If you fail to secure it well, you can end up with jerky camera movements.)
Set the long piece of plywood on the floor at the camera position you choose for the shot. Put the skateboard on top of the plywood. The plywood serves as a flat surface (even if you are shooting on a flat floor) for a more assured, smooth traction against the ground. This will also allow you more control over the direction of the wheels. You will have a better chance of getting really usable shots without the jerky movement.
Put the chair on top of the skateboard and secure the chair to the skateboard with gaffer's tape.
Secure the camera on top of the Styrofoam, then put the whole rig on top of the chair's pole. There are many ways to secure the camera to the Styrofoam. The simplest way is by attaching the bottom of the camera to the Styrofoam with gaffer's tape. Wrap more tape around the the sides of the camera and the Styrofoam. Use more tape to attach the camera and Styrofoam to the top of the chair's pole.
Make a test shoot once you are sure that the camera is securely set on the dolly. With this simple setup, one person can do both the camera and grip operations. And if the camera is carefully secured, it’s just a matter of working on the movement of the dolly. Track in, track out, or side track as needed while filming.
For a very low-angle shot, remove the chair and put the camera (with Styrofoam still attached) on top of the skateboard. You can adjust the height by adding a block of wood or a pile of books. If using such, wrap them carefully and tightly with plastic before securing the camera and Styrofoam to them.