In many cases you should be able to thin enamels with generic hardware store thinner, but it may be advantageous to test it on a small quantity of your enamel paint.
It will not work with acrylics, Tamiya or otherwise. If you are using Tamiya or Gunze acrylics, the best options for thinning are, in order of preference,
- Tamiya acrylic thinner,
- 91% (or higher) Isopropyl alcohol
- Ethyl (denatured) alcohol
- Distilled water (in small amounts)
You may see references to people using lacquer thinner with Tamiya acrylics. This may work with Tamiya's proprietary "lacquer thinner" which seems to be a less aggressive blend (possibly having a higher alcohol content and lower content of aggressive organic solvents like acetone, toluene etc) than the "generic" hardware store variety lacquer thinners. you may also see some references stating that Tamiya acrylics aren't "true" acrylics because they can be thinned with lacquer thinner. This is not the case. Tamiya acrylics are in fact true acrylics because they cure by polymerisation of acrylic binders in the paint. The reducing medium (ie thinner) doesn't determine whether a paint is acrylic based.
Some other acrylics, eg. Vallejo, are not (or are marginally) compatible with alcohols and should be thinned with the manufacturer's proprietary thinner or to an extent, distilled or demineralised water.
Generic enamel thinners will be suitable for cleaning your airbrush when using enamels, but not necessarily when using acrylics. Lacquer thinners should be effective in cleaning both types of paint. You can use Isopropyl or Ethyl alcohol or an ammonia based cleaning agent like Windex to clean your airbrush when using acrylics - dont' use the manufacturer's thinner, it's too expensive.