Looking for a job when you're unemployed may be unpleasant, but it's easy to do. You can shout from the rooftops that you are on the market, and fly your resume behind a plane if you think it will help.
Conducting a job search when you already have a job is trickier. Exactly how tricky depends upon your exact work situation. Are you looking because you hate your job? Are you only scouting to find a better situation or more money, but are otherwise happy? Do you love your job, but feel compelled to keep an eye open just in case something better comes along?
Whatever your specific case, there are some clear rules to follow. These won't necessarily help you find your next job. They will, however, keep you (hopefully) from burning bridges with your current employer. That may not seem important, but it's about protecting your reputation and doing the right thing even when it may not be noticed.
Never use office resources
A few years ago, my then-business partner and I were pretty open with our small group of employees. Our company was only going to operate for a couple of years and the jobs they had were the jobs they were going to have. We made it clear there was no advancement possibility and that we would happily help them look for better longer-term jobs as long as they looped us in when they were starting a search.
That did not stop the occasional part-timer from using our printer to print resumes without asking us, nor did it stop employees from using work-provided laptops during working hours to search for jobs.
We were open to employees leaving and happy to help them do so. Not asking before using our resources, however, was rude, and at a traditional company it may even violate policy.
One of the big challenges when it comes to getting a job when you have a job is finding time to interview. In general, it's better to say "I have a personal matter to attend to" than offer a specific excuse that's not true.
Should you get the new gig and quit your old one, your former boss will probably realize that you were lying about being sick or having a bunch of school conferences. It's OK to omit, but there's no need to lie.
Don't badmouth your current employer
In an interview, it's normal for a potential employer to ask you about where you work now and why you want to leave. Focus on positive reasons for leaving like "being ready for new challenges" or "wanting to push your skills." Perhaps don't be as cliched as those answers are, but don't use the question as an opportunity to say bad things about where you work.
It's fine to cite facts. If, for example, the job is a promotion, it's OK to say "my path to being a vice president was blocked by an incumbent who showed no signs of leaving." Don't say "no promotion would be worth it because upper management is incompetent."
There's a clear theme
Be graceful as you try to leave one job for another. Avoid any urges to slam the door on your way out and always be professional. That means executing a job search on your own time, and when you get a job, giving a full two weeks' notice (or more in fields where that is proper).
It may not be satisfying, but going out the right way sends the proper message. You old boss may not appreciate it, but others who work there will, and your new employer is sure to notice as well.