One of the common themes in anything book-like, at least using Roman alphabets and thus left-to-right format -- and this carries through to most posters and lunchboxes and t-shirts as the same people make them with the same habits developed -- is that the eye is supposed to be led to about 2/3 to 3/4 of the way down the right side of the image. The reason is simple. When you pick up a book in the bookstore and hold it up to examine the cover, especially if you are right-handed, that spot that's being pointed at is covered by your thumb. If the artist can subconsciously lead you to move your thumb (following the flow of the image) then you are thatmuch closer to opening the book and reading the blurb on the inside, and thus a lot closer to buying it. Tiny thing, but it works wonders. The yellow spots indicate the 'hotspot' which is the place of focus that the lines in the image flow to, which provides momentum for the eye to keep travelling right to the thumb. Sometimes the hotspot is right under the thumb, even. The lead-lines are in red. Not only do lines lead to where you want to put the eye, but that point should be the point of the most noticable contractin the image. If you have another high-contrast spot elsewhere, it will lead the eye away from the hotspot. Another point that is important for most commercial at is the concepts of 'text-zones' and 'safe-zones'. Text zones are areas where the designer is going to put text, and generally include the bottom 1/6 and the top 1/3, but sometimes that varies. Text zones should be free of 'clutter' and 'busyness'. They should be low-contrast and it's generally best to avoid actual objects in them. These are good places to fill with sky, simple pattern, the Frazetta-ish concept of 'umimportantness' (in painting, you can make 'unimportant' areas less attention-drawing by not 'finishing' them, sort of. Taking amore impressionistic approach and not giving them full life keeps them from upstaging the focal points. Another thing that is really important to composition, and something I dno't think most people on this site realise or ever think about, is the idea that you don't crop your picture afterwards, you plot your frame first. Needing to crop your image to look nice is amateurish and often obvious. Deciding on a set aspect ratio to work within FIRST will always improve your work at least somewhat. It's a good idea to measure out the aspect ratios of such things as novels, game manuals, notebooks, posters, and so on, and work within those rather than one of your choosing. It makes your work more commercially viable. Finally, it's also a good idea to consider treating your work as if it's going to be something like a book cover or record sleeve or whatever even if it's not. Why? Because if you submit your work to an art director or even have a lot of people look at it, they are going to be (whether it's 'right' or 'wrong' comparing it at least to some degree with the work of others. If you're going for fantasy, sci-fi, action, and so on, yuo're going to be compared to Boris Vallejo, Frank Frazetta, Larry Elmore, Michael Whelan, Darrel K. Sweet, Rowena Morrill, Keith Parkinson, Brom, Clyde Caldwell, Jeff Easley, and even maybe Phil Foglio depending on your style. Doesn't matter if you're doing this digitally or not. Thatmeasn that making your work look like a book cover or game manual cover or comic cover or movie poster or whatever is going to make you look like your know what your'e doing,because you're using an arrangement that's similar to 'pro' work. Remember, oftne 'pro' is a word that really means 'got noticed in The Stack'. If the commercial aspects of this sound like selling out, consider this: starving to death is stupid, and working a day job telemarketing or doing phone support is a lot more like selling out, to most, than doing art for a living and living it and breathing it day in and day out. Suffering for art is fine and dandy, but I'd rather not, thanks much.