Nowadays everybody is conscious about his or her online security or privacy. It is a debatable subject for now. Due to the advancement in online activities this becomes all the more important. 
   Theoritically its a very difficult thing to achieve. No system is cent percent secure.... So what is the point in discussing it ?? But there are ways in which you can avoid it in most of the cases. Some tips regarding it are as follows (the tips are very basic and intermediate or complex cases are not discussed ) :
   1) Install Firewall 
   2) Use latest and regularly updated version of Antivirus.
   3 ) Visit the vendor's website for the security patches.
   4) Make it a habit of reading the postings on various computer security newsgroups.
   5) Never ever give your passwords or other sensitive data through insecure ways.
   6) Use "Verisign" or other services for secure mails.
   7) If you are using public computer try to see whether any mischief software is running behind . You can do that by running " drwatson ".
   8) Never give your IP address or share your PC on net. Whenever you do so, use reliable and secure methods.
   9) Make it a habit of scanning mails before opening it ,though it may be from a known source.
  10) Look at log files for the possible attempt of intrusions from outsiders.
  11) Assign proper rights to users if you are in a network.
  12) Change your passwords regularly , and try to have different passwords. Avoid any patterns in passwords.
  13) Remember it always that no system is full proof so there is always a margin for improvement.
   ...more to be added later...
  If you follow these and some others you can be very much confident about your security. The danger increases manifold when you use a public computer. So in that case practice maximum precaution. Once you are in a habit of doing these it will not take more than a minute or two. There are many more tips but due to limitations I have skipped those. You can ask me for those by mailing me .