You can also use denatured alcohol, aka methylated spirits. It seems to "wet" better tha n isopropyl alcohol. It also allows you to thin right down, say 75% thinner without losing adhesion.
Note that with either sraight ispropyl or denatured alcohol, gloss Tamiya acrylics will lose some sheen. For gloss, I'd recommend sticking with X-20A or Tamiya lacquer thinner.