Any interface design starts with structuring information and assigning priorities to elements. A simple rule to remember that was defined long before the beginning of the internet era, also, often neglected by designers. This tip has evolved from the user's perspective, who reads from left to right. General, important, and commonly used elements placed at the top left corner, because this where the user starts the reading.
For example, a website logo is better to position to the top corner as it is the most general piece of information which is placing the website visitor into a context. Placing navigation links after the logo is a right approach as the function of the links it to outline the topics brand is dealing with and distributing to more specific pages. Further the line, worth to place the main feature, or call to action to give the visitor guidance of what expected from him or her.
Elements that are compounding information by the topic have to be from left, or above the specific information. Similar items or functionalities go beside each other extending the sequence to the right.
Worth to mention that for apps and websites with languages spelled from right to left, like Hebrew and Arabic should swap sides. The principle still applies, yet the sequence is just inverted.
For touch screens, like mobile phones and tablets, structuring works slightly different. Navigational functions should be closer to hands, meaning at the bottom, so the user taping on elements does not hide the rest of the screen with his or her hand.