The top portion of a website is very important because only the first few inches will be visible on a standard computer screen before scrolling. Bold primary colors should be used sparingly for emphasis. You want your text to be readable. See these examples . Images w Consider size and color relative to your overall page design.
File size is important.
Large files take time to download. A choice for no design is a choice for bad design. Establish a simple layout grid and style for your pages and use it throughout your site.