Cancellation: It's no fun if you fall ill before you leave and can not go on your trip. To claim though, you have to buy your insurance policy when you buy your trip. Not all insurance policies cover cancellation, so please read the policy wording relevant to you carefully.
Lost or Stolen Gear: most travel insurance policies have a per-item value limit - make sure its high enough to cover your gear or choose a policy that allows you to increase the limit.
Medical expenses over and above evacuation: check that your cover includes emergency treatment while away and transport to bring you home - remembering that insurance providers will usually insist on getting you home as soon as you are fit enough to travel.
Adventurous Activities: look carefully at what your policy covers - you may find that you are not covered to do all of the adventurous activities that you are planning while you're away.
Personal Liability: Accidents happen. If it's found to be your fault and someone decides to sue you, you want to be covered.
Is it safe to go there? Make sure you check the your Government's Travel Warnings and keep up to date with the latest travel safety advice on the road. You may not be covered if you choose to go to a place affected by war, terrorism, civil unrest or environmental disasters (like volcanoes, earthquakes, floods) and other major events where you may be at risk.