It's relatively easy to search for a job when you're unemployed. You have nothing but time and don't need to make excuses or take time off in order to interview.
When you're looking for a job while you already have one, however, things get a little dicier. Interviewing can be a major challenge depending upon how much flexibility you have, and even small things like answering a phone call are not always easy.
When you're looking for a job while employed, there is a right way to go about things, and there are some clear mistakes. These aren't rules -- it's more a case of doing the right thing, because that's the type of person you should want to be.
Never use company resources
Just because you have access to the copy machine does not mean you should use it. The same goes for using a work computer to check job posting sites or even to answer job-search–related email. You might be able to use your company's assets for other personal things -- like checking social media or streaming a movie while traveling -- but you should still keep your job search separate.
Be as honest as you can
Many interviews take place during the workday, and most come up on short notice. That puts you in an awkward position of needing to take time off -- at least part of a day -- without being able to plan for it.
Obviously, you probably don't want to tell your boss you have a job interview. Instead, don't tell the full truth, but don't lie either. Tell your boss you have a personal situation to deal with. In most cases, that should be enough to shut down further questions (though you may be asked if everything is all right).
An even bigger challenge than the first interview is when a company wants you to come in again quickly. When that happens, it involves taking even more time off without being able to say why. Again, you have to be honest without full disclosure.
Will your boss suspect something? It's possible, but it's just as likely he or she thinks you have a health or family situation that you need the time off for.
Always be positive
During the interview process, it's likely you will be asked why you are leaving your current job. Make your answer a positive one about the opportunity before you. Never say bad things about your old employer. That will be a potential red flag for the person asking the questions, as it will make him or her wonder if you're a malcontent who will soon be saying bad things about your new employer.
You can point out facts that are making you look. You can say something like "My shift is 7 to 3, and I really would prefer a more traditional 9-to-5 day," but never dwell on the negative. Even if your boss is a jerk and the company just cut everyone's salary, it's still better to be upbeat about the new opportunity rather than putting down where you are now.
See both sides
If you work for a company that treats you well and you're looking to leave in order to advance your career, make sure you are considerate of your current employer during your job search. Don't start looking right when a new project starts or during peak season.
Treat your company with the same level of respect with which it treats you. It's reasonable to look for a new job. But if a new employer wants to schedule an interview on a day when you were supposed to lead a major sales pitch, you owe it to your current employer to either find another time or pass on that interview.
Take care of yourself and your needs, but be responsible and professional in how you conduct your search. That might require being selective or even turning down an in-person interview because the timing doesn't work. Doing that may set you back, but it's important to protect your reputation even as you prepare to leave.