Size and complexity of the kit should be tailored to your intended type travel, for example how far off the beaten path are you going, how difficult is the terrain, and what risks do you take on your adventures. You can get by with a simple off the shelf kit when 911 services are likely to be within a few minutes away, but if you are 100 miles from nowhere you need to be able to stabilize and maintain a patient for much longer. being in the wilderness exposes you to many different opportunities for injury or sickness; trauma from an accident, burns from a fire, environmental (heat, cold, animals etc.). Even a simple cut may need several dressing changes before you get to civilization or medical help. Most importantly make sure to get at least some basic first aid instruction, if possible orientated toward outdoor adventure travel. Also remember to check your kit on a regular basis to make sure everything is in good shape and nothing has expired. Personally I carry an extensive kit with lots of trauma supplies and a separate boo boo kit for the every day scrapes and bumps. As my wife and I travel alone much of the time, several different types of communication are as instrumental as the first aid kit itself to summon help in a timely manner
