Just to add to the points Trebla has made, one of the most important things to keep in mind with a resume is appearance and formatting. Substance over style is a thing with CVs, but keep in mind that employers have very little to judge you on, so how your resume looks can carry a lot of weight. Employers glance over CVs quite quickly, so you need to ensure that it is easily readable. Furthermore, a well designed CV will reflect better on you as a candidate, because it adds an air of professionalism and sophistication to your application. Think about it, would you be more or less inclined to advance someone's CV if it looked like it had been composed in 5 minutes by a 10 year old? Whilst it may seem like a superficial thing, it does have an impact. Earlier in the year I overhauled my CV only in terms of appearance and that led to a significant improvement in the progression of my applications.
Building on from this, another key thing to keep in mind is CV improvement. If you arent getting anywhere with your current CV/cover letter, then that is usually a sign that you need to change things. The definition of insanity is doing the same thing over and over whilst expecting a different result. As you get further into your job search, you should begin to pick things up in terms of what employers look for - you should be using that to develop your CV. During my job search I made four or five major CV/Cover letter revisions - each revision managed to improve my success rate. By the end, my last CV revision had a super high success rate in terms of call-backs (I should note, I only used that CV for non-grad positions).