Policy and guideline pages should:

• Be clear. Avoid esoteric or quasi-legal terms and dumbed-down language. Be plain, direct, unambiguous, and specific. Avoid platitudes and generalities. Do not be afraid to tell editors directly that they must or should do something.
• Be as concise as possible—but no more concise. Verbosity is not a reliable defense against misinterpretation. Omit needless words. Direct, concise writing may be more clear than rambling examples. Footnotes and links to other pages may be used for further clarification.
• Emphasize the spirit of the rule. Expect editors to use common sense. If the spirit of the rule is clear, say no more.
• Maintain scope and avoid redundancy. Clearly identify the purpose and scope early in the page, as many readers will just look at the beginning. Content should be within the scope of its policy. When the scope of one advice page overlaps with the scope of another, minimize redundancy. When one policy refers to another policy, it should do so briefly, clearly and explicitly.
• Avoid overlinking. Links to policies, guidelines, essays, and articles should be used only when clarification or context is needed. Links to other advice pages may inadvertently or intentionally defer authority to them. Make it clear when links defer, and when they do not.
• Not contradict each other. The community's view cannot simultaneously be "A" and "not A". When apparent discrepancies arise between pages, editors at all the affected pages should discuss how they can most accurately represent the community's current position, and correct all of the pages to reflect the community's view. This discussion should be on one talk page, with invitations to that page at the talk pages of the various affected pages; otherwise the corrections may still contradict each other.

See also: https://en.wikipedia.org/wiki/Wikipedia:Policies_and_guidelines