1) Don't use a generic "Objective" statement. We're all well aware that you're trying to get this job to use your skills that you've learned. Instead, tailor the objective statement on your resume to suit the job you're seeking. For example, if you're looking for a job in a store, as a cashier, you might say something like, "To ensure that every customer who walks past my cash register feels important, and cared for." In other words, tailor each resume to the job you're looking for, based specifically on each company you send it to. If you're sending a generic resume to everyone, you haven't spent any time on it, aside from the initial writing of said resume.
If you're not going to spend any time on writing the resume, why should I spend any time reading it?
2) Proofread any written communications with your future employer. Yes, even if you send it from your phone. Glaring grammar or spelling errors make you look careless.
3) Show up on time. I cannot stress this enough. Nothing short of the second coming of Jesus should delay you on your interview date. Leave your home two hours earlier than you think you'll need to get there. Why? Traffic delays happen. Spills happen. Rips and tears to your clothes happen. Subways get held up for train traffic, or lost power, or idiots holding open the door. You show up to the area that your job is going to be at very early, and you now have a bit of time to chill out, and relax. If you're late, someone else who wants the job badly enough to show up on time will win out over you. Even if your excuse sounds valid, the employer will still be thinking, "Well, how many other excuses will they come up with if I hire that person?"
4) Even if you get another job before your interview date, send a communication to that person who arranged it. It's a bad idea to burn bridges. No job is ever 100% certain. If you leave a good impression on the person in charge of hiring and firing, you have a chance of getting that job later on, should the one you got right now not pan out.
5) Know about the company you're applying to. I'm not saying that you need to go spend money there, but it helps to do some homework on the place you want to work at.