D.I.Y. MAINTENANCE: Cleaning Headlights (or plastic light casings)

Do-It-Yourself car maintenance on,

Hazy or Yellow Headlights

Over time headlights tend to get hazy and could start turning yellow.
Great explanation as to why this happens.
Procedures would vary depending on the severity of the oxidation, or haziness, of the headlights. For lightly oxidized headlights (low severity), two rounds of polish should suffice. For a moderate level of oxidation, rubbing compounds would help.

The example illustrated below is of moderate severity.
For a more severely oxidized headlights, try sanding and following these procedures.

3 Products used in this project:
Turtle Wax: Rubbing Compound (using an applicator pad)
Turtle Wax: Polishing Compound (using an applicator pad)
Nu Finish: The Once A Year Car Polish (wanted to use a 3M polish but not a lot of stores stock it)

Problem:

Fig 1: Headlights in the sun, BEFORE

Fig 2: Headlights in the shade, BEFORE

 Step 1:
Pop the hood. Then clean the headlights with water or applicable cleaning solution and dry. Recommend outlining the headlights with masking tape for precaution.

Fig 3: Masked but still hazy

Step 2:
Apply rubbing compound, and wipe off before any excess hardens. Repeat if necessary.

Fig 4: Rubbing compound applied

Step 3:
Apply polishing compound and wipe off before any excess hardens. Repeat if necessary.

Step 4:
Apply polish and wipe off after a light haze appears.

Fig 5: Waiting for the polish to dry.

After doing-it-myself:

Fig 6: Fixed headlights in the shade, AFTER

Fig 7: Fixed headlights in the sun, AFTER

A professional cleaning should get it close to looking new but for a Jane, it'll do.

Note: I have heard of the toothpaste method and have not tried it. Toothpaste should be doing the same thing as the rubbing and polishing compound is doing, which would be removing the oxidation from the headlights. In general with DIYs, the purpose is to get the job done and as long as it works for you and is safely done, win win win. Whichever method is used, I recommend applying some kind of polish as the last step to protect the headlights. In addition it will reduce the frequency of cleaning the headlights, meaning less work in the long run.

Update:
Tried the same procedure on a friend's car later in the evening and here were the results.

Fig 8: Honda Accord DIY headlight fix

References:
Youtube clip: 'Car DIY: Fix for yellowed headlights' and comments.