Brush Painting...

  Tamiya's paints are awfull, I agree, however doing a couple things can give decent results. Golden's  Acrylic retarder (available at most art stores) seems compatable with tamiya, and appears to extend the 30-second drying time associated with tamiya's flat paints! the other is your choice of brushes. if you can get them  tamiya's brushes do well, but even better are windsor and newtons series of  red sable brushes - accept no substitutes, take good care of them- they will last forever, and make brush painting fun again! also don't work tamiya with the brush! one or two swipes, let dry and re-coat later. Tamiya Aside , and if you need to stick to acrylics I recently aquired Gunze's line of aqueous colors and have NEVER seen acrylics that handle like this stuff. they are all semi-gloss giving a much longer drying and handling time, and seem to really like tamiya's surface primer (highly reccomended for acrylics!). In the realm of oils I cannot reccomend Testors for brushing. (very  inconsistant mixes and to much carrier) Humbrol gives great consistant results, and white ensign  is quikly becoming my new favorite. don't be afraid to touch up  acrylics with oils. expirement lots and find your happy medium. brushing ain't so bad -J

I never brush paint Tamiya acrylics.  as you said, they are great for airbrushing but horrible for brush painting.

I use Windsor artist's oil paints or Model Master enamels for brush painting.  They are thicker and easier to brush than Tamiya acrylics.

(I don't own an airbrush.). White is the color I most hate to brush-paint. I'd rather use a spray can or white primer to paint white.

Floquil Reefer White comes highly recommended.