There’s a series of books by Jim Krause (Color Index, Layout Index, etc) that are useful and easy to navigate through. They’re good starting points. They run about $25 each, but you can sometimes find them on sale. (HOW Magazine frequently has discounts on design books. Check out their website.)
Besides resources, I recommend studying things like the Communication Arts design annual and other design publications. Look at the color schemes and think about why they work. Study the layouts, draw them, analyze the pieces of them and see how they create hierarchy.
I’ve taught classes in layout and design, and the first assignment I give is to pick out 25 layouts (posters, ads, whatever) and draw them. They don’t have to be perfect, but try to get the proportions about the same–even if you’re just drawing a box to represent the product, another box for the logo, and so on.
Going to websites to get color schemes is OK, but don’t rely on it. A good designer uses color to further an idea, not just make something look pretty. Sometimes a surprising addition or adjustment to a “standard” color scheme can take a design from expected to extraordinary. Never underestimate the impact that thoughtful (not computer-generated) color selection can make.