I think everyone should have decent online stalking skills. Not because I condone stalking, but because knowledge is power -- if you don't know how to find people online, how do you know what people can find about you online?
Googling yourself is like checking your credit report for inaccuracies: it's only effective as a preventative measure if you do it thoroughly and routinely. Whether you're looking for yourself or a friend (no judgment), here are five tips for finding out anything, about anyone, online:
Plug everything you know into Google.
It doesn't matter how little you know about the person you're looking for, your search is going to start with Google. And it should, because Google is a powerful tool (especially). But if you don't know anything particularly identifying about the person you're looking for (such as their email address), it's better to skip the fancy search hacks and go straight to plugging in keywords. Open up Google and type in everything you know about the person in keyword format; for example, "sarah los angeles writer tech." Even if you only know their first name, keywords related to their job, marital status, location and school will likely bring up social networks or other identifiable results.
Use Facebook's People Search.
If no social networks pop up in your initial Google search, you may need to go into the social networks themselves. Facebook is the most popular social network, and it has the most robust search engine, so you should probably start there. Facebook's People Search lets you search for people by filling in one or more search boxes: Name, hometown, current city, high school, mutual friend, college or university, employer, and graduate school. If you know one or two of these things about your subject, you can narrow down your search and then browse through the photo results.
If your subject has no social media presence, try to find their friends and family members; it's possible they're hiding their account behind a fake name. If you have no idea who their friends and family members are, and you know their full name, use a free people search like Intelius to look up relatives...and then hunt down those relatives.
Individual data points don't mean anything unless they can be connected to other data points to make up a person's online presence. Once you have several facts about your subject, you'll need to use your brain to make connections and fill in the blanks. For example, if you know your subject's name, job title, and location, you can probably find their LinkedIn profile. On their LinkedIn profile, they've probably listed their undergraduate degree and when they graduated from college, which means you can work backward to figure out approximately how old they are.
Remember people are not very creative.
If you can find someone's username, Twitter account, personal email address or YouTube profile, you may have hit gold. People, for the most part, aren't very creative when it comes to mixing up usernames (or), so they've likely recycled that username many times over. Start by plugging their username into Google, but also look through social networks, forums such as Reddit, and blogs for old comments or posts.
A picture is worth a thousand words.
People recycle usernames, passwords, and social media profile pictures. Grab their profile pic from their Facebook or Twitter account and plug it into a reverse image lookup such as TinEye. TinEye will scan the image and then spit back all other instances of that image that it finds on the web -- this is a great way to find now-defunct social media profiles, old LiveJournals, and online dating profiles. You can also use Google Images to do a reverse image search by going to Google Images, clicking the camera icon in the search box, and uploading the image you want to search.