I would definitely take
annietwinkletoes suggestion to use the white fluidline! but in terms of using paints as a base, i've found that it's worked for me. what i do is first apply a thin layer of foundation or concealer to the lid then follow that with a thin layer of the paint, from lashline to brow. then i take a little more of the paint and apply a second layer, this time only up to the crease. you have to work kind of fast with the paints because i've found they work best as a base if you don't allow it to fully dry before applying your eyeshadow over it. that way, the shadow really 'sticks' to it. another step that i sometimes add (if i know it's going to be an extra long day or night) is to use the benefit brand eye primer, F.Y.Eye. i use this after the layer of foundation and before paint.
however, having different shades of paint depending on the eyeshadow(s) you're wearing helps too. for example, for my green shadows, using chartru paint (which is green) helps the colour of the green shadow really pop as opposed to using it with something like stilife or untitled.
one last point (i promise!) is to consider the brush you're using and how you're using it. generally, brushes that have stiffer, more densely packed bristles tend to pick up [powder] shadows really well. then you would apply it in sort of a patting motion, almost as if you were 'packing' it on. blend afterwards with softer bristled brush if the colour goes on too harsh because of having 'packed' it on. i'm sorry this got so long, but i hope it helps!!! it's worked for me.... good luck