You may find many of articles on this topic and various flavors of views on what to do and what to not. Anyway, who cares about general guidelines unless they are framed under some strict and legal action? :) Don't worry, I will bore you here, but will share you some points that seems unethical to me. I am one of you, don't confuse me with HR, Admin, Account or organization owner. :)
Occasionally, I use my office internet for personal emails, internet banking (for bills like mobile, credit card, insurance) and for book orders (rarely but true fact). Though, I make myself feel better when I see others doing online shopping/exploring items, news reading, random surfing and so on, but the fact remains unchanged and my opinion is that it is not 100% ethical, right? :(
Misuse of office technology/property
This is where most professionals spare their time. It degrades your performance if you spend some time on random surfing between your work.
- Office internet: It should not be misused by downloading your personal stuff or doing personal surfing. Most organizations maintain an internet log and your activities are recorded. One of my co-workers was working in a company (I will not disclose the name here but it is situated in Udyog Vihar Phase-V, Gurgaon, India) and was fired on the basis of logs.
- Office Phone: Though most Indian cellular service providers are offering low calling rates, still some greedy people misuse their office phones for personal calls. It should be avoided.
- Office Scanner/Printer: I have seen in many organizations, people use office printers for their personal print-outs. Don't ever try to print your kids school's assignments, :) that must be avoided.
Misuse of flexibility
- Gossip in cafeteria
- Out of office for hour(s)
There are some kinds organizations who consider only 2 card punches (your office-in and last-out punch) to calculate your work hour for the day. But all organizations are not kind enough to provide you this type of flexibility. They even separate their work-area and other areas like washroom, cafeteria and so on which force you to punch your card every time you go to the cafeteria (that is itself inside your office!)
Never accuse your colleagues on their knowledge
Why accuse others? I personally believe in "Karma" and follow "help silently, God sees it and we are bound to God only". Remember, if you have sound knowledge on certain skill set, others may have on a different skill set or have expertise in a different area. People joins an organization from various companies where they have worked in various environments, domains, technology and differ in expertise/skills.