1. Research where you are going. In some places like mainland China or Japan tipping can be considered insulting. So do a little reading, save your cash and don't get labeled a rude tourist. For general ideas on tipping in prospective countries we've put together a brief list:
2. Remember to read the bill. As previously noted many restaurants and hotels will automatically add a gratuity and should be giving the tips to the staff.
3. If you're unsure what to tip, just ask. Most people will give you an honest answer and let you know what is adequate.