Make sure the words you use mean the same thing to your audience as they do to you. Bimonthly is a good example. It can mean every two months or twice a month. Which would you choose if it applied to your paycheck? Which would you pick for visits from relatives who hold you in low esteem?
Biweekly and biyearly present the same challenge. Be concise and pick a synonym–fortnightly to say every other week or semiannually to imply twice a year–or be specific by saying “the first and fifteenth of the month.”
Apply the same principle to words in your industry or business niche. Don’t assume your readers know your jargon, your trade names, or your clever but confusing acronyms and abbreviations.