Happy to share what I do.  I've been fooling with acrylics for a couple years now and Some Days
it works good...... other times not so good.
    I just use the CHEAP stuff from WalMart.  I like buying all sorts of colors that I'll probably never use but at
$0.89  a bottle who cares.  Any way.... I have a half bubble plastic tray that I came across as packaging
somewhere along the way and I use it with a cup of water.
  I simply dip the brush in water and then grab a touch of paint from a bubble and some times
dilute it and some times use it straight.  That gives me stains and paint in varying shades and colors
as I pre smear all the parts.with either color or stain.   This by the way gives me are the variants that
make it look like I really worked hard at the colors (when I didn't).
  I even stain over parts that I sprayed white to start with. Makes an interesting aged look to the paint.
  Anyway That's all I'm doing.  Simple Cheap Easy that's me.  But most of all FUN.
=Steve

here's the bubble paint holder: