Rule 1: Unless you are conducting learner testing, do not experiment with positioning of buttons. There is a logic why the next button is positioned in the right bottom corner and why the exit button is positioned in the top right corner. Understand the logic before you experiment.
Rule 2: Always use radio buttons for single select MCQs and check boxes for MMCQs or multiple select questions.
Rule 3: Buttons should look clickable. Non-buttons such as placeholders, text boxes, and so on should not have the affordance of being clickable.
Rule 4: When selecting a font and font size, remember that readability is more important than visual appeal.
Rule 5: Colors should be selected using the color wheel. Do not assume that certain colors go well with each other. Check it out.
Rule 6: Ensure that there is a clear visual hierarchy. The contents of the screen need to be well-balanced.
Rule 7: Ensure that all elements such as feedback boxes, text boxes, placeholders, and so on belong to the same family.
Rule 8: Use grids to design your screen. Ensure alignment and proper spacing.
Rule 9: Ensure easy accessibility for those features that the learner is likely to use often. For example, the next and back buttons
Rule 10: Ensure that the icons and the graphics used are self-explanatory.