Are you doing it 'in the field', as it were... acrylics that is.
Don't you have to take a pile of stuff out with you? Or do you make sketches and notate them and work them up into something when you get home?

One of these days we WILL go painting together at some tearjerkingly wonderful site, I hope.
J
x
Gotta dash - going to a gig in Uffington tonight