There are two types of travel delays in an air travel. Ones you cannot plan for (such as a broken down plane) and those you can anticipate:
Weather Delays- Airlines will not generally compensate you for weather delays. It is up to you to take them into account when booking air travel and getting to the airports on time.
Security Check-In Delays- Some airports are better than others in getting people through the security checkpoints in a timely manner. If you have two airports that are close to your take-off point you may want to consider which one is the better airport to land at.
Airlines On-Time Percentages- the Bureau of Transportation Statistics has a top-notch website that can help you pick the airline that is most likely to get you to your destination on time.