Most pony blush isn't shiny like their eyes and symbols. Once you've mixed your paint to a color that matches the original blush, dab a small bit on a Q-tip. Paint it on with the Q-tip, making sure to fade the edges. You can wet the Q-tip with nail polish remover or water if you need to thin the paint.
Photos courtesy SourDoughStomper.
Photos courtesy Miss_Tuneful.
It can sometimes be difficult to mix paint colors just right and to keep a steady hand when painting. The more you practice the better you will get at this. You're also touching up a surface that has already been started for you, which makes it much easier! Once you've mixed your color to match the pony's eyes, touching up scratches and scuffs is relatively easy.
If your pony's eyes are so bad that you have to remove them completely, it's a good idea to mix your paint before you remove the eyes so that you have something to compare for a color match. If the eyes are so far gone that you can't tell their original color or what they looked like, try asking for closeup photos at the MLP Trading Post or the MLP Arena. Other collectors are usually more than happy to help out.
Fine, soft, paint brushes tend to work well for detail work like this. You can seal and replace the shiny top coat on the eye with a gloss glaze or Mod Podge.
Photos courtesy Kanthaka.
The trick in choosing a brand of glitter is finding one that is both the same texture and color of the pony's original symbol. If you look closely, most glitter symbols are a mix of both silver and colored glitter. Look for glitters that describe their texture as "micro" or "ultra fine". After you've chosen your brand and color of glitter, paint the symbol with glue. Be sure to use a glue that won't run so that it holds the shape of the symbol, and that will dry completely clear. Aleen's Tacky Glue is a good choice. Sprinkle on your glitter and gently smoosh it down if needed to flatten it.
Rarely, the jewels are missing altogether. These can be replaced using jewels found at craft stores, but its difficult to find jewels that are just the right color, size, and shape. Hatsetsut at the MLP Arena sells reproduction twinkle eyes that are gorgeous.
With any paint job involving a pony, how well your project turns out depends on two things: Your eye for mixing colors & your skill at painting. The more you practice, the better you will get at this. You're also not trying to paint a Van Gogh here, you're just touching up a surface that has already been started for you, which makes it way easier! Once you've mixed your color to match the pony's symbols, touching up scratches and scuffs is relatively easy. If the symbols are so bad that you have to remove them completely, it's a good idea to mix your paint before you remove them so that you have something to compare for a color match. You can seal your paint job using a gloss glaze or Mod Podge. If you're using acrylic paints, you can slowly mix in water until you achieve the exact thickness that you want.
I saw this mentioned at the Arena but I don't know where the information originally came from. Solarcolordust.com sells a powder that changes color when warmed. Their website shows it used in all sorts of things. It certainly seems to have potential for use with magic message pony symbols.
Molded symbols have a tendency to break off and are often lost, especially with the precious pocket ponies. If you can find someone to lend you a pony that still has the symbol you need to copy, you can potentially make a replacement using a casting kit. The other option, is to simply sculpt the missing accessory using something like Sculpy or Apoxie Sculpt. The same acrylic craft paints used for touching up symbols can be used to paint them, cover them with a glaze to reach your desired shininess. Photos courtesy BlackCurtains.
Courtesy MayCrestMom, these photos show the process for removing Princess Pony symbols. You can use metallic craft paint to fix up scuffed symbols.
Photos courtesy Starshinecustoms.
TinyShinyUnique created a nice color matching guide for Swarovski crystals. She provided these lovely photos and most of this information. Look for size SS12 or PP18. You can buy them in the quantity of your choice at Artbeads.com.
Colors pictured (in order): Peridot, Amethyst, Light Rose, Light Sapphire, Rose, Sapphire.
Other colors, such as Ruby and Fushia, are close matches to some G2 ponies' eyes, while not exact. These size and color matches apply to adult G2 eyes. The size babies is PP14. If you know the names of good color matches for babies,please e-mail me! Also check out The Lavender Lagoon Eye Crystal Colour Guide.
Chipped jewels can be removed with a needle. Any super glue or craft glue of your choice can be used to hold the new jewels in place. TinyShinyUnique recommends pushing them into place using a nail stick. More info can be found in this thread: Online Reference for Matching G2 Crystals
Some collectors prefer to mix the glitter and glue together and then paint the mixture onto the symbol. Some also draw the symbols on with a silver glitter pen before gluing on the colored glitter, versus mixing silver and colored glitter together.
Cartwright's Sequins offers ultrafine glitter with lots of color choices. Craft stores are also a good place to find it.
Here's a cute little video tutorial from Yum-Yum at the MLP Arena: My Little Pony Glitter Tutorial.
G2 - The jewels in G2 eyes are easier to replace. Swarovski crystals are expensive but have been reported to be an exact match.
Photo courtesy LostPony.
Photos courtesy Lostpony.
This is what a TE pony looks like with the original paint intact. Photo courtesy MysticIceDragon.
And this is a Twinkle Eye that has lost it's paint. Photo courtesy MLP Sunsparkle.