I think, most people will agree the hardest job hunt is the first one as you enter the workforce. While it helps if you've had some internships/co-ops, it's still very challenging to land the first full-time job as you start a career. Engineering is a career where most of your peers will be on the same footing as you, you're all very bright. Rising to the top is hard, and finding that edge is something everyone struggles with. On top of all that, you don't have the negotiating power you do when (if) you ever change jobs in the future. Walking away from a job that doesn't feel right is hard when you have no alternative at the time, but reneging on an agreement could tarnish your reputation in the future.In this situation there's a few things you can do to get ahead. First of, you need to be wholly committed. It's going to be very challenging to do this, school, any extracurriculars, and everything else in life. However, spreading it out means you lose any negotiating from potential offers. When employers know you have other interviews, they know they can't delay in getting back to you. Stress that you want to work with the employer you're talking to, but hint that (honestly) you're ultimate goal is to be employed. If you get an offer, let any other employers you're waiting to hear from know. Give them a chance to compete.Additionally, going "full-go" will keep you sharper in interviews. Always read up on employers and be ready to answer simple questions about them. Practice STAR questions (Situation, Task, Action, and Response), google that for some prompts. It's also important that you have questions for them, have a lot because many will be covered in the course of an interview. Be sure to try and still have a few at the end. My favorite is, "What's your favorite part about this job?" Always a good sign when they don't hesitate and have a lot to say. Don't ask about wages, period. It will come up at the appropriate time, from them. I've seen this sink a lot of candidates. Dress professionally, be courteous, and kind to everyone you interact with. They're not just hiring someone to do a job, they're hiring someone they're going to be working with. No one wants to work with jerks or rude people. Always be honest. The truth will come out sooner or later, and if they can't trust you, then they won't want to hire you. If there's something where being honest is going to hurt you, be prepared to explain how you grew from an experience or work on it. (e.g. failed a class, but studied very hard to pass it next time). Be proud of accomplishments, but not boastful/arrogant. Know how to give a proper handshake, gender does not matter. A firm but not crushing grip is an old custom that is no less important today than ever before.Do anything you can to stand out. If you have an interesting story that speaks well of your character that's great to work into an interview response or in conversation. Do you speak another language? A good volunteer experience? Captain of your intramural team? Funny story? Cool place traveled to? You want them to see your name later reviewing candidates and remember you, positively. If possible try to find something you have in common that you're both passionate about, outside of work. This is where you can stand out from your peers.As Luis said, follow-up communication is a must. Be brief but thankful for their time and consideration, something this makes all the difference. A lot of getting the interview in the first place is the hardest part. This will be critical, as many companies will receive lots of inquiries and be reviewed quickly by HR staff. Another route is hone your networking. It's tough to do, but any way you can make connections with potential employers will help you get your resume to the right people faster. Utilize friends, family, teachers, student chapter meetings with companies, anything to get that first contact. LinkedIn can help you a lot with this.Next, but probably first on your to-do list is to hone your resume. At this point in your life, you'll need to keep it to 1 page. No more, no less. Make sure you include contact information, major accomplishments, work history, school information, etc. As you get experience cut down old sections. Nothing should be too wordy, as it should make them want to ask you questions. Don't make anything up, but don't down play your role either. Not "worked as manager at McDonalds", rather "Managed 10 employees to maximize efficiency and coordinate staffing hours". Read other people's resumes and have them look over yours. Spelling/grammar errors will stick out like a sore thumb, and are easy for you to miss if you've been staring at it for hours. Again LinkedIn can serve as a long form resume, you can cover a lot more there and put a link to your page on your resume. In an increasingly paperless world, always submit your resume as a PDF to ensure they see it as you intended. Word opens differently on different machines and you can lose all your formatting.
Lastly, don't get discouraged. Getting rejected is never enjoyable, and while it may feel personal, it likely wasn't. There are countless factors that come into making their decision and a lot of them have nothing to do with you. Be tenacious and confident, as best you can, and eventually something will work out. Never give up!