I shamelessly use the cheap stuff—Delta Creamcoat or Americana hobby paints. I get them at Hobby Lobby or WalMart for about $1 each.
For almost every blue uniform (French, Prussians, Swedes, British Artillery, ACW Union, FFL) I use "Midnight Blue" and dry brush a light beige to bring out highlights.
For French I sometimes dry brush a lighter blue (True Blue) before the beige. The uniform's probably darker than real life but I like deep colors/contrast.