Just recently I bought a beat down wooden toy tractor on a fleamarket. I costed me 4€. Before giving it to my son I decided to give it a little facelift.

Tools involved:
Screwdrivers
3mm and 5mm drill bits
sandpaper (80 to 320 grit)
handsaw
cutting knife
hammer
pincers
file

Materials:
wood dowels 5mm
welding wire 3mm
wood beads
blue masking tape 6mm from 3M
standard painters masking tape
spray paint (red and clear)
primer for plastic

Step 1: Taking Apart and Sanding

The title says it pretty clear: take everything apart, keep all the parts (for now) and give the wood parts some treatment with sandpaper. Start with a rough grit to get rid of the old coating and work yor way up to the fine grit to create a smooth surface.

Step 2: Replacement Parts 1 - Steering Wheel

The original steering wheel was missing. Instead of just replacing it with some wooden disc, I decided to make wheel and column out of one piece of 3mm welding wire.
From a wood dowel with the right size I made a bending template. I basically drilled a 3mm hole trough the middle of the dowel and made a centered cut into the top side.
I got the bending right in the second attempt. After cutting off the excess wire, I soldered the gap to avoid injuries. To finish I hammered and filed the lower end of the steering column flat to fit it into the existing steering joint.

Step 3: Replacement Parts 2 - Lights

The original lights were gone. As replacement I found some wood beads in the perfect size and shape. I drilled the existing holes up to 5mm to glue in matching dowels (don't force it or the beads will split). Then I cut them to size and drilled a 5mm hole into the side of each light. After that I sanded off the old paint, cut off the leftover dowel and rounded the back edge of the light. Then I glued in the dowels on the sides and prepped the lights for painting.
On the tractor side I redrilled the existing holes to 5mm diameter

Step 4: Replacement Parts 3 - Decoration

When I bought it, the tractor had some mirror strips nailed to the sides and front. I decide to let go the front decoration.
For the sides I wanted something out of wood. I had some 5mm dowel left from the previous step. So I cut them to the same length as the original mirror strips. Then I split them into half lengthwise with knife and hammer (be careful on that), sanded them flat and rounded the ends. To prep for painting I sticked them on some painters tape I fixed to a piece of wood.

Step 5: Paint Job

Before painting I used Autodesks Sketchbook Pro on my tablet to make some sketches. I decided to go for the simplest version (KISS rules), red with some silver accents.
The shape on the tractor I did freehand with 6mm masking tape from 3M (sorry, I got excited and forgot to take a picture before spray painting), the rest of the tractor I covered with standard painters tape. Same on the wheels.
The tractor hood got several coats of red, as well as the seat. The steering wheel I painted black, the lights and decoration strips silver. The wheels got a layer of plastic primer first, on the wood and metal I didn't use any primer.

Step 6: Assembly and Coating

In this step I added the lights and side strips. After the glue had set I gave all the wooden parts several layers of clear coating.

Step 7: Final Assembly and Show Off

After the clear coat had hardened through I assembled the remaining pieces. I was very satisfied with the result, but this was nothing compared to the smile on my sons face when he saw the tractor! He loves it!