For best results:

Professional enamel "One Shot" paint and then automotive clear coat for sealing that comes in small "shaker" bottles after fine sanding with 2000+ grit paper.
This is a clean, sand, paint, sand, paint, sand, paint, final clear...step by step process, until undetectable WHEN THE INSERT IS LIT.
This includes spot testing from the underside for a "shine test", which may require additional paint layers.
This may also require overpainting existing non-damaged insert areas to "blend" the paint.
Yes, this process is tedious, but provides quality results.

Other enamel paints are not nearly as good in quality, or are too thin for application without a thickening agent will require more coats.
Use clear coat that is curable under UV light LEDs or lamps to speed up the process.
Use micro fine art brushes with rubber grips, good lighting, and magnification glasses or headset.
Quality enamel paint will not smear it or run after drying upon application of clear coat on top, nor will it easily chip it applied directly to clean surfaces.
Cheap brushes split and fall apart.
The first step is obtaining the correct materials and equipment.
You also may need to make your own blackline templates, rubbings or retrace artwork from scans to set up the border regions.
Learning how to do proper masking without playfield damage is equally important.

Remember the 6P formula:
"Proper preparation prevents piss poor performance."

The playfield must be completely clean, free of contaminates, and all wax removed.
Inserts must be completely flush with the playfield surface, or a person is going to defeat their efforts in the short term.
Reset them accordingly, prior to starting any work.

Minor insert wear repair does not require a full clear coat process.
Major wear or serious planking and/or paint splitting due to environment or poor cleaning methods (especially with water based cleaners, Windex, and all sorts of bad things I have seen in the past) does require a full coating, if you want the damage to be nearly unnoticed.

The photo below is an example of what can be completed with experience, patience, and time.

The method I described applies to all types of playfields and coatings from any manufacturer era, but be aware a person cannot just paint on top of remaining clear coat, tuff coat, or lacquer as that needs to be sanded first or removed without removing more paint.
Paint needs surface tension to adhere correctly.

The major challenge for most is skill, becoming an expert at mixing paints for color corrections, and knowing how to use materials and methods properly.
Practice on junk playfields first, and consult with an professional artist on techniques and enamel application.

Recognize that use of any type of aftermarket decals even printed against wear with high quality UV inks has one major downfall, the edges. They affect ball travel, especially in games such as Fish Tales due to decal location.

I may develop a Youtube video painting guide, at some point.

Keep flipping.

Nip IT PF.jpg

On wpc games that have chipped away the clear on the inserts, I mix up a small batch of 2pak clear. Using a small brush or toothpick, drop the clear into the lower/chipped away area and use the tip to spread the clear around to the edges. Slowly keep adding drips to fill in the area to get as close to level as possible without going over.

From there you can decide to do insert decals or paint touch ups.

In regards to the fish wear, Bay Area Amusements sells a decal for each of the fish. I have also seen a single decal that does all four fish at once but couldn't find it with a quick google search.

http://bayareaamusements.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=GS-861&Product_Code=&Search=&Per_Page=-1

I always use an airbrush and Createx acrylic paint for touch-ups. Harbor Freight sells one for about $10 that may not be the best, but is adequate. You will need to clear or put mylar over any paint work.

Typically you want to re-paint the entire area until you get to a break (like a black line) since it's extremely difficult to exactly match paint.

If you're new at restoration I would do the decals on the fish and throw some mylar on the other spots so they don't wear any more and forget about them since they're not really that bad. In all cases level the inserts first (see Vid's guide for a complete playfield restoration).

https://pinside.com/pinball/forum/topic/vids-guide-to-ultimate-playfield-restoration

Little Shop of Games for the full decal

Recognize that use of any type of aftermarket spot decals, not full overlays, even reverse printed (in some cases) against wear with high quality UV inks, proper color matching, and correct adhesives has one major downfall, the edges.
Even full overlays have their own pitfalls, if the playfield is not properly sanded and fully prepped for application.
All individual decal edges affect ball travel even at a 1 mil thickness, especially in games such as Fish Tales due to decal location.
Alignment is also critical, or the owner can get ghosting, if the existing insert printing is not fully removed.
That is why so many people waited so long for CPR to reproduce the playfield for that particular game.