Have a Plan
A job search is a job in itself. You need to keep track of all ads you see and respond to, noting the resume and the cover letter you sent to each. Tracking and documenting this info will help immensely when a company you applied to six weeks ago calls you, giving you the chance to reference the job in question and all your other research. To that end, finding a company hiring, researching the firm, and figuring out who you may know there, all with the possibility of finding the side or back door that lets you in, is a far better approach than just firing in a resume through the front door (namely HR).
Look and Act the Part
School's over. It's time to enter the "real" world. With that comes the need to present yourself more in line with others who are already there. Some changes to consider: Start by getting rid of an email address that describes your interests (e.g. firstname.lastname@example.org) instead of something more professional. Keeping it simple, first and last name or similar, is more acceptable. If you are going to give your cellular number as your phone contact, then be sure the voicemail is professional and that it states your name in the message. Get yourself a suit and be sure to keep it clean and pressed for every interview, even the ones where you know the place is casual. You're not on the team yet, so wearing the uniform before being drafted is a bad omen.
Start off by ensuring that you know where you are going, how to get there, and that you leave yourself enough time for traffic and other unexpected delays. Then when you get there, do not walk in much before 10 minutes prior to your interview. Everyone you see, from the security guard to the receptionist gets a smile, a nice greeting, and, where appropriate, a firm handshake. Oh, and before you walk in, at the least put your cell/device on silent/vibrate...and do not answer it or text or similar when waiting and definitely not when in an interview. Bring copies of your resume for each person you may be seeing...and those you did not know you would be seeing. Ask each person you see for a card.
A simple thank-you note sent to all those with whom you met goes a long way...and when you don't send one, it gets noticed in a bad way. Calling to follow up when told "we'll be in touch" is usually not a good move, but shooting a tactful email to your contact, only after they have failed to get back to you in the timeline they shared with you, is a better approach.
Think of your job search as a test. You need to prepare, focus, and execute, with the reward of a passing grade possibly being a job offer.