Like Paint, the goal is to use the least aggressive methods and products to get the job done, and attain desired results.
Today, there are so many products on the market for such, and can be gotten anywhere, all the big auto stores, and even wally world carry a plethora of such resto products.
One may find that a mild plastic or paint polish will give the desired results, or one may have to resort to more aggressive methods, and products, such as first using wet papers of varying grits to remove damage, and then refine the smoothness of the lens material. One might find 2000 grit useable, but then again I seen lenses that 2000 grit does almost nothing for, that I had to start with 600, then 1000, then 1500, then 2000, then buff-polish with DA and Compounds, and then Polishes.
Down here in the desert, vehicles that are just a few years old look like somebody sandblasted the headlights, and severely yellowed and hazed.
Always mask your work area before you begin.
One large problem with lens resto, is that after all that work, and your lenses again look good, they will again deteriorate over time, dependent upon the durability of the protectant you use.
Waxes, and Sealants are usually poor at protecting, and within a month's time the lenses again are starting to fog-haze, and look like ass again.
The more permanent coatings will be better at protecting, and staving off degradation again.
Any polishing will over time remove the Lens's protective UV coating, and with a 1999 Model, I suspect there's very little to none of that left anyway.
I know there are many over the counter (OTC) products today said to be more durable, such as Wipe New, and others, and are worth a try.
Otherwise, other products from the makers like Carpro (CQuartz/CQuartz DLX), GTechniq, Optimum, and others would be the products one should seriously consider.
A product such as CQuartz-CQuartz DLX should easily last a year on Lenses, and other Trim.
Not cheap initially, but in the long run more economical, and saves you mucho time, having to continually go back again and again to deal with such.
Of course the other option is replacement, there are literal 100's of lenses-housings available online, and at that auction site. One can go stock, or custom.
I replaced all of mine on my '97 about 1-1/2 years ago, all stock in front as I didn't wish to change the look, or the headlight pattern on the road at night, and went with a slightly mild custom light for the rear which looks very close to stock.
Mark