Hello, /ic/ here trying to beat his own autism and go out and paint, for anyone interested in en plein air painting i recommend watching James Gurney's videos, they're amazing inspo
https://youtu.be/jmFlycEexQA.
His books are also good, maybe a bit too rambly but it's good knowledge.
Alla Prima by Richard Schimid is the more hardcore option and also pretty gud.
Everything is easily downloadable searching in the links of the /artbook/ thread' OP on /ic/