And here is some of her work on Art Stack (very nice, especially the dream series).
Here's Leona's cover for Kati of Terra Book 1: Escape from the Drowned Planet
Kati 1 - Escape from the Drowned Planet
Kati and Mikal's escape from the alien slaver Gorsh.
Amazon U.S.: https://www.amazon.com/dp/B00811WVXO
Amazon U.K.: https://www.amazon.co.uk/dp/B00811WVXO
While in the early stages, she imagined three alternative Katis, what we might call Anime Kati, Space Girl Kati, and Hippy Kati. We had a couple of dozen people vote on their favorite, and Anime Kati prevailed quite handily. As you can see, the real Kati draws mostly from Anime Kati, though she is somewhat older looking and with the more confident look of Space Girl Kati. :
Space Girl Kati:
A lot of people liked the cover for Kati 1, it really seems to draw the eye. It's always difficult to estimate the effect of cover art on sales, but is the best seller of the series, though the first book of a series will usually have the highest sales. The other two books also use the Kati figure, but in a less artistic, more photo-realistic setting.
My not entirely scientific conclusion is that a really good artist can help a book, a lot, if he or she can capture the spirit of the characters and/or the story. Mind you, that might apply more to genre fiction, especially SFF or Romance, than in some other categories.
Leona also did artwork for The Witches' Stones series, but I will leave that for another blog.