1) Run antivirus software, adware, and antispy routinely on your computer. I set it to run at least once a week using it's built in scheduler at a time I wouldn't being using the computer. i.e. 4 am
2) Being weary of logging into your accounts on other peoples computer especially in internet cafes and such. You don't know if the computer is being monitored or the computer is full of spyware. I don't even log in on my mother's computer since I'm sure it's full of spyware. If you must log on, make sure you clear the browsers cache or browse in privacy mode.
3) Watch out for phishing scams in your email which load a website that looks like the real deal but then steals your log in info. i.e. www.ac.com/dreamstime
4) Never send your log in info and password via email. No legit site will ask you for the info they already have on file
5) Use a password that is over 6 characters and has numbers, letters, and symbols and make sure it's not words commonly found in dictionaries. Changing between uppercase and lowercase may be useful also.
Anyway, be safe. The internet can be a dangerous place but if you are prudent, it's the great resource of knowledge.