There are many places to find good thoughts and suggestions about how to travel safely within your own country or when traveling abroad. Here are a few good resources that are available online.
Safety Tips and Resources provided by National Government Agencies
1.) A Safe Trip Abroad (US Dept of State) - This is a good resource no matter where you are from.
2.) Travel Safety (NZ Govt) - A good list, especially for those on long-haul and adventure based travel.
3.) Travel Smart (OZ Govt) - Good high level safety, security and other travel preparation considerations.
Other Online Resources offering good travel safety suggestions
1.) General Travel Safety Tips - A good, easy to read travel safety/security guide.
2.) Tips for Safe Travel (Lonely Planet) - Good practical suggestions from the savvy folks at LP.
3.) Safe Student Travel (About.com) - Some good tips for young travelers eager to get out and see the world.
4.) How to avoid pickpockets (Self-defender Net) - Some good tips for avoiding those nasty pickpockets.
These are just some of the online resources that can be easily found and used to learn how to travel safely. Additional information can be found in travel guidebooks and please make sure you investigate the safety situation of the country or area you intend to visit prior to travels.