Pxl > feel free to choose a format you desire (hence the initial tutorial - choose a format you like. normally, its either landscape, widescreen, rectangular or vertical portrait). In terms of resizing, you have to consider two things. Final format. are you planning to print this or purely as a lerning opportunity or for web distribution
If so, here is what you should consider
[ol]
[li]72dpi - web/screen usage[/li][li]150 dpi - poster size[/li][li]300dpi A4 or magazine print[/li][/ol]In terms of pixel by pixel size, if you double or triple the current thumb you have now to around 4-5k width, it should give you sufficient resolution to paint in large painterly strokes that when you ultimately finish, and downsize to say, half its final value, you have an almost photographic painting.
Remember, upsize early on or once your finer details and colours are added you mgiht regret it.
Erandil > I think the thumb needs more work, to provide a good heirachy of values. Do you wnat me to do a paintover to see what i can come up with?
DIM > Excellent start, however the victorian thumb is in colour and some perspective adjustments will be required. This is harder to do in colour than in greyscale. Hence, we started the intiial composition as a plan or abstract study followed in greyscale thumbs
Mu > Youāve got the basics of the instruction right. now try to compose those elements not as lines but as solid greyscale shapes. The instruction for this theme is mroe freeform, allowing you to paint any kind of enviroment to include some rural and industrial elements combined with some steam punk machinery if youāre up for it
I guess i better start composing and writing the perspective chapter next!