Consider trade secrets, especially when your commercially important secrets are unsuitable for patent or copyright protection.
Consider the formula for Coca-Cola and its “natural flavorings”, which dates back over 100 years. Even if the formula could have been patented (unlikely), the patent would be long expired. The formula might not be even eligible for copyright since it is a list. In any event, copyrights by now would be both expired and useless. This is because copyrights for a recipe would only cover the sequence of printed words. However as various closely guarded trade secrets, the formula remains valuable (the trademark, of course, is almost priceless).
In addition to recipes, trade secrets can include production methods, marketing methods, computer software, and the like. Pretty much any information that gives a business competitive advantage, and is not generally known, is a potential trade secret.
Trade secret protection is very narrow – unless you can prove to a court that you carefully guarded the secret, such as with NDA, and someone with access to the secret then misappropriated the secret, you are out of luck. If someone figures out the secret by other means (e.g. reverse engineering), there is no protection, even for Coca-Cola.
However, if you can convince the court that trade secret theft occurred, you can request injunctions (e.g. block disclosure), damages (your economic harm caused by the theft), and possibly even seizure of materials and/or attorney fees.
Until recently, trade secrets were only handled at the state level. However, in May 2016, the federal Defend Trade Secrets Act of 2016 (DTSA) was signed into law. Trade secret theft can now be handled in either state or federal court. This type of theft can now be charged under both civil and even criminal law.
So if you are doing a startup, think about which of your non-commonly known information gives you a competitive edge. Where appropriate, apply for patents and trademarks and register copyrights to prove copyright ownership. For the rest, although some disclosure may be required for marketing and fund-raising, try to limit this disclosure, and take positive steps (e.g. restriction of access, nondisclosure agreements) to preserve not-generally-known information that is competitively important.