You will spend a fruitless day whatever your search method is if you do not know the search basics. You will probably search first for external source of information when the most important source is yourself. What information you already hold will be your key to your search.
Maybe someone has been calling you or sending you letters anonymously. All telephone and address are sorted in directories under an owner. So look in directories to stop wondering who among your old buddies might be pulling this prank.
You have list of names for your baby and you want to make sure the one you chose is unique, or at least not a name of a criminal somewhere. Search engines are the most popular information portal nowadays. Type in the name you want to know about and you will get something related to it with 8/10 chances.
You have to inform your brother that his psycho ex girlfriend is hunting for him and on the way to his place. With instant messaging your warning can arrive within the day you sent it. Or if you like to go to him personally but you are unsure how to get there, you can acquire a map for the location that comes up as you type his email in Email Searches.
Instead of wondering what you do not have, focus on what you have. The School or College you shared with the friend you are looking for maybe still attached to his name online no matter how famous he has become.
It is also helpful to give instead of taking. Advertise your search online or in other media with your contact number and name. People familiar with you might respond and help you out.
Get familiar with these basics and you will surely get somewhere near the person on your mind.