There are a lot of things that can make an impression on your prospective employer - the presentation of your CV, your appearance or your cover letter. However, there are also a few small things that are sometimes overlooked; things that can hinder your application or start in a new job.
This brings me on to the subject of commitment, this is obviously something that a lot of hiring managers look for, especially now that it is not uncommon for graduates to leave their first jobs only after a couple of months.
Showing commitment during your application and onboarding process gives a good impression with your prospective employer, mainly indicating a sense of loyalty and longevity with the company.
Try not to re-schedule calls or interviews with the hiring managers. There are obviously times where you will have to because of certain circumstances but try not to unless it's really necessary. If you do, it makes it look like you can really organise your time well and if you do re-arrange too many times, it just looks like you aren't taking the process seriously.
This also links to attending appointments on time, showing that you want to be there and are again serious. You might also have to come back on several occasions to complete the process. They are inviting you back because they want to move forward with you; so don't insult them and show that you want the role.
Remember that there are alot of other candidates out there that are applying for the same jobs as you, especially as a grad so don't take your opportunities for granted!
All the best with your job search!