1. Avoid Ambiguity
2. Be Concise
The longer a contract is, the more likely that it will contain problems such as mistakes and ambiguous language. You should strive to keep contracts as short as possible, but no shorter. Each sentence of the contract should have a clear purpose and serve to reduce complexity.
As much as possible, avoid the use of technical jargon; write in plain English wherever possible. When appropriate, simplify phrases into single words (such as "propose" instead of "make a proposal"). Use the active voice instead of the passive voice, which tends to make sentences longer.