Here’s more (and nicely practical) advice on this topic (a topic one didn’t need to worry about much not that long ago…)

How to Defend Your Online Reputation: Five Tips
It’s not what other people think of you that matters. It’s what they can find out about you on the Web that will affect your ability to get a job or promotion, rent an apartment, buy a house, be accepted into the school of your choice, or find the love of your life.