With the anxious feelings about going to an Interview, it can be easy to mess up by not having the best manners. Not manners like keeping your elbows off the table mind you, but good etiquette. In a job interview setting, it can be easy to make silly mistakes that might offend someone and in turn cost you the position. Here are a few good ideas to help you keep your interviewing manners in check.

Show up early. Being late to an interview will make a lasting impression, but not a good one. Especially if you are unsure of the location, it is best to leave with plenty of time to find the correct building and account for possible traffic jams. If you arrive more than 15 minutes early, just wait outside or in the car before entering the building. It could be terribly uncomfortable if someone has an interview before you do and is still waiting in the lobby. This is true for both you and the other person. Be early, not less than 5 minutes but not more than 15 minutes. Think of it this way: If you are late, it will signify to your potential employer that you may ALWAYS be late. In getting to work, and on deadlines.
Have a great handshake. You don't need to put on the vice grips, but don't "dead-fish" your potential boss either. Your handshake gives off a good first impression, so make it count. A firm, confident handshake is the way to go.
Everyone deserves respect. You need not only impress the person you are interviewing with. It could be very possible that the receptionist or someone sitting just off the waiting area is in on the decision making. Receptionists are often asked what their first impression was of you, so treat everyone kindly. You just really never know who is watching.
Never be a no-show. If you figure out you're really not interested, call to cancel. Don't waste everyone's time by just not showing up. You never know in your career whom you will have to work with down the line, so it's best to not make enemies before they even meet you.
Be prepared. Research and know something about the company you're interviewing with. If you know something about the company, it shows interest and gives you a great leg up. Don't waste their time interviewing if it truly isn't a company you can't work for. Also, bring along all of your reference information, resume and portfolio. Make that preparedness really work to your advantage.