I haven't read it yet, but am intrigued. This is what I would suggest (some repeats of previous suggestions):

- post a freebie starter sample of the first chapter or so - it should preferably get to a point where something just happened and a reader wants to know more.

- don't be afraid to post on random book forums. You can always ask people to mention your book on GoodRead once completed for example. So if friends and family on Facebook join that you could get some free publicity.

- As a kindle user I often look for less pricy alternatives when looking at unknown books. That way I may get two or three books for the cost of a book from more well known writer. So a competitive price should get more readers.

- the format is important, don't make it Kindle only. If available to more formats you have a chance of getting more readers. Especially since some people still use their home PCs, laptops, etc to read books online.

- I like the idea earlier mentioned of having the word Scarlet in scarlet, as it jumps out and catches a viewers attention.

- as for the cover, people will expect what is on the cover to be in the story.
A bad book cover example would be a book called "the immortal dragon" with a cover showing a hero figure having decapitated a dragon.

When it comes to color, less is more in my opinion.
If there is too much color it steals the attention from what you want them to see. Especially if there is going to be one scarlet word mixed with another words in a neutral color.

If you have a girl, a plane and a dragon - people will expect a girl, a plane and a dragon in the story. One can always hide or partially cover some detail to leave some details for the imagination. For example only seeing half of the dragon or only part of the plane. In a world with dragon it will likely be a strong influence. A steam car could be shaped like a dragon, borrowing the artwork on ancient Chinese canons. The wings of a plane could be inspired by the shape of dragon wings, to avoid being Earth history identical.
For stories with a lot of intrigue, another possibility would be cowled figures moving in shadows, perhaps whispering in some prominent figures ear while holding something behind their back. If this is a different planet than Earth, then it can have any type of vegetation, so a blue tree with pink and red leafs could be fine provided it doesn't take center stage. It is there to add some color or provide a means to show how different the world is. As you already have steam tech and dragons it is only there to fill in a potential void.