Paint pen effects

I'll admit, I don't really know what I'm doing with paint pens. Obviously there are many hours of YouTube out there, but I don't have time to dig through it all, so I've read a couple of articles (sooooo much quicker than video) and dived in. First, we have the garden around the house. One challenge is to match the colours to the stills from the film of My Neighbour Totoro, which seem to change quite a bit. Then to remember that I've only seen the stage show (still looking for a DVD), and so I want a nice-looking model. It's not about authenticity. AK's Off White seems a reasonable base colour for the tree trunk and ground. Arguably, they should both be brown, but we are in a fantasy land. The plants are picked out in cheap pen Dark Olive, which looks really nice, but cried out for some highlights. With paint, I'd dry-brush, but that's not an option with the pens (I wonder if I could drag colour from the pen onto a brush? One to try), so I simply picked up high areas on the ground…