what's the best way to achieve the flat paint look

I use Dullcote to get a matte finish and to seal and protect the paint.

NAPTHA...The stuff you put in zippo lighters. will matt gloss paints..add a few drops to your mix..test spray ..not flat enough add more drops...test spray...till you get the finish you want[ test on scrap] this also works with matt paints that are a bit old and tend to lean towards the semi gloss.....

Try looking closely at the paint bottle before you buy. For FS (Federal Standard) colors, the first number will tell you flat, gloss, or satin:
17875=Gloss white
27875=Satin white
37875=Flat white
Hope this helps a little.
Gip Winecoff

I think enamel paints are always gloss unless it states on the bottle that it is flat. To acquire the flat look just spray it with a clear flat coat (after applying decals of course)

Jack

I suppose having that glossy finish in fact gives you more benefits. That way the decals will cling to the surface better. You can thereafter spray the model with a flat coat.

Gloss paints will usually result in a glossy (or at least semi-gloss) finish regardless of the amount of thinner you put in. If you want to spray on a flat finish right away, you can add a flat base, if one is available in the brand youre using, and mix the same to the paint before spraying. Be careful, though, as too much flat base will give you a "snowed" finish (apparently, the dissolved flat base re-crystalizes after drying and leaves white-colored accumulations). Try spraying the mixture on a old model first and see how it dries up.

Hope this helps.