Testor's Model Master Series is excellent for the most part, and you can usually get most colors. They have both a regular and airbrush thinner.
To get that meniscus look on the sides of the letters, you need to thin it out and let the thinner evaporate, that's the wash method that FantaZ mentioned. You can also do this when you have larger areas and you need the paint to flow smoothly and not show brush lines or obvious signs of different puddles being poured.
Sometimes I like to use Pactra Formula-U because of it's excellent adhesion properties, generally fuel proof and nice finish. The paint is much thicker than other paints I've used, and if applied properly will actually flow out and eliminate brush lines. Be aware that this stuff takes HOURS to dry properly, but the finish is worth it. I found it from my R/C Boat hobby, and we use it there in the engine compartment and anywhere you need water / fuel proofed.
Pactra's Racing Finish has some beautiful colors and because it's made for Lexan Bodies (R/C) it adhere's really well, but it will chip.
With the exception of the Racing Finish, you can find Clear Gloss / Satin / Flat in spray or bottle.