This FB page is run by a teacher in Australia – she has some great painting ideas and it’s worth taking a look:
https://www.facebook.com/404151036453828/photos/a.404155703120028/1435450876657167/?type=3
This instagram features my hero Quentin Blake, you may know some of his illustrations from the Roald Dahl books. I just love love love his free expressive style.
Vicki Arnold’s website has 50 drawing tutorials which I think are quite good